Out of the silence came the voice of Ned Rector.
"Help, I'm pinned down," he groaned. "Get me out of this awful hole."
"I'm coming as soon as I can get free of what's on top of me," answered Tad. "Is everybody else all right? W-a-l-t! Mr. Phi-ipp-s!"
Tad struggled desperately and in a brief time succeeded in freeing himself. What had happened to the guide and to Walter he did not dare to think.
First upon getting clear of the obstruction that pinned him down, he rushed to Ned Rector and succeeded in releasing him without great difficulty. Neither boy was hurt much.
"Where's the other two?" cried Tad in a voice of anxiety.
"I don't know. Don't know where I am myself," groaned Ned.
"Hurry, help me find them."
Together the boys groped about in the black tunnel.
"I've got one," called Ned.
"Which one?"
"I don't know. Yes, yes, it's Walt. He's breathing. What shall I do?"
"Drag him over to one side. I've got Mr. Phipps here. I'll have him over there in a minute."
Tad began tugging, with hands under the shoulders of the guide, understanding instinctively that he must get him where they could work over him and try to bring him back to consciousness.
Something whizzed by in the darkness, the rush of air nearly knocking both boys over, and leaving them trying to catch their breaths.
"Wh--what's that?" gasped Ned.
"I--I don't know," answered Tad. "Yes, I do too. It--it was a car returning on the other track for a load of ore."
The lad's knees went weak under him when it came to him that he had only a second before dragged the unconscious figure of the young engineer from that very track.
Now still another sound startled them. It was a roar heavier than any that they had heard before, and as near as they could tell, it was from the direction that they had come.
"Hurry, Ned!" shouted Tad Butler fairly electrified by the thought that suddenly flashed over him.
"What is it? What is it?"
"I--I don't know, but I think it's a car of ore rushing down the grade toward us."
"We're dead ones, then!" cried Ned.
"Be quick, Ned! Grab Walt and run as you never ran before!
"On, on! Keep to your right so you don't get on the return track. Oh, Hurry!"
Tad had already gotten into action. Once more grasping the guide by the arms, the lad ran backward with his heavy burden, with almost marvelous speed under the circumstances.
He was none too soon. Back of him he could hear Ned stumbling over rails and ties with his burden. Then came the heart-rending crash.
The car of ore had plunged into the wreck of their empty car, hurling rocks in all directions. Had they remained where they had been, there would have been none left to tell the story of their experiences.
"I guess it's all over," shouted Ned. "But, there will be more, soon, and some of them may hit us."
In obedience to Tad's command, Ned dragged Walter along a few rods further, where on a curve both boys laid down their burdens.
Tom Phipps under the rough treatment that he had received was stirring and making an effort to sit up. Tad helped him along by slapping him vigorously between the shoulders. Ned was shaking Walter almost savagely.
"Wake up, Walt! Wake up! What's the matter with you?"
Walter groaned.
By this time Tom Phipps had partially pulled himself together.
Tad's heart leaped with joy.
"Walt will be all right in a minute, I guess," Ned informed him.
"And so will Mr. Phipps."
"Where am I?" asked the young engineer.
"We've had an accident, Mr. Phipps," replied Tad. "How do you feel?"
"As if I had been put through the ore mill. Did we have a smash?"
"I should say we did?"
"Who's hurt?"
"Walter was knocked out too, but he is coming round now. Ned thinks the boy is not hurt very badly."
"No, I'm half scared to death, but I'm all right otherwise," answered Walter for himself.
"Which track are we on?" demanded Phipps suddenly, trying to locate his position.
"Our own. You nearly got run over on the other. I pulled you off just in time."
"I'll thank you later. There must be a cross cut near here. If we can find it we'll be able to get to a point where I can telephone them to hold back the cars. They'll fill the tunnel before they know anything has happened, if I don't get word to them at once."
"I should think they would miss the cars."
"They should," answered the engineer. "Is your friend able to walk?"
"How about it, Walter?" called Tad.
"Yes, I can run if it will take me out of this terrible place any sooner."
"Then we'll run," decided Tom Phipps. "I must have gotten an awful hit on my right leg, for I can scarcely bear my weight upon it."
"Shall I rub it for you?" asked Tad.
"No, we haven't time. We must look for that cross cut, which leads into the number eleven drift. Keep to your right, boys. We are safe here now, but not on the other track."
"I know that," answered Tad. He shuddered as he recalled the black, projectile-like object that had whisked by him just after he had pulled Mr. Phipps from the return track.
There was still another reason why the assistant superintendent was so filled with anxiety to reach a place where he could notify the terminals to stop the cars. He did not confide this to his young friends, not wishing to disturb them any more than they had been.
All hands started on a trot, now stumbling, now falling, but without a single murmur, or protest.
"You are a nervy bunch of boys. Never saw anything to equal you," gasped the engineer. "I can't forgive myself for getting you into this wretched mix-up."
"You never mind us. We're all right," answered Tad brightly. "I'm sorry you got knocked out so."
"Here's the cross cut," cried the miner. He had paused and was cautiously feeling his way along the wet, slippery wall.
The boys breathed a sigh of relief.
"Now run as if the Indians were after you. I'm in a bigger hurry than I ever have been in my life."
And run they did.
The boys had no idea what Tom Phipps's reasons were for urging such haste upon them, but they knew they must be urgent ones.
Tad found himself wondering what new peril might be facing them. He decided that the assistant superintendent must be seeking to protect the company's property by stopping the sending of more cars through the tunnel. Yet, if this were so, why had the guide urged them to such haste.
"No," said Tad to himself, "it's something that we don't know anything about. But unless I am greatly mistaken we are going to find out pretty soon."
In this the boy was right. They were to find out what it was that Tom Phipps feared, and in a manner that they would not soon forget.
The narrow cut through which they were now rushing was little higher than their heads, and was very narrow, so that by raising their elbows they could barely touch the sides and keep themselves in the middle of the passage way.
"Look out for a turn just ahead," warned Phipps. "After that it is straight away."
The turn which they made a few seconds later, Tad imagined, led back toward the place where the car had started from. But they came to the end of the passage abruptly.
They caught a faint click, and instantly they were surrounded by dazzling light. As soon as they became used to the brightness they discovered that they were in a sort of chamber which looked as if it had been worn out by constant and long action of water.
Instantly upon switching on the light, the young engineer sprang to a telephone on the wall. Tad observed that the wires from it followed out into the passage through which they had entered.
The assistant superintendent was telephoning now, and the lads listened intently.
"Hello, hello!" called Phipps in an impatient voice. "Yes, who's this? Acomb? Say, Acomb, there's been a wreck on the number one track just west of here. Two cars smashed, one loaded the other carrying myself and some young men, guests of the company. Don't let any more through until the wreck is cleared away. Send an empty along with the wrecking crew so we can get out. What's that?"
Tom Phipps shuffled his feet about nervously on the stone floor.
"Hurry then, hurry! Yes, we're all here, but hurry!"
The boys instinctively drew near. They imagined that they could hear each other's hearts beat, so tense was the silence.
He turned halfway around to glance at the boys.
"Is it anything serious?" asked Ned in a strained voice.
"I hope not. I can't tell you just yet. We shall know in a minute... Well, send some one for him," he snapped, answering something the man at the other end of the line had said to him. "Hello, hello! That you, Bob? Did Acomb tell you of our predicament? Yes. What I wanted to say was don't for goodness' sake send out the red car while the line is blocked."
"The red car," repeated Ned and Tad in one voice. Neither knew what it meant, but impressed them just the same.
"What, gone? gone?" groaned Phipps. "Are you sure? How long ago? Ten minutes? Shut off the current! Quick! I hope so."
The assistant superintendent hung up the telephone deliberately and turned toward them.
The boys observed that his face was white and drawn.
"What, what is it?" asked Tad.
"There's a car of dynamite coming through the tunnel on the number two track," announced the young engineer calmly, thrusting both hands deep into his trousers pockets.