Updated

More than 1 million rounds of ammunition, a cache of weapons and a tunnel were found at a man's home after an explosive fire that forced a neighborhood evacuation, authorities said Friday.

Crews worked to fortify the tunnel, which measured 5 feet wide by 8 feet long, to ensure it was safe. It appeared to be at least 10 feet deep and led into a back yard, authorities said.

The fire Thursday afternoon at the home in Norco, about 45 miles east of Los Angeles, caused some of the ammunition to explode.

The man tried to run back into the house after firefighters arrived and had to be restrained by sheriff's deputies, Riverside County sheriff's Deputy Juan Zamora said.

After the blaze was extinguished, crews discovered metal and wooden boxes of ammunition for shotguns, small handguns and assault rifles.

On Friday, sheriff's deputies and agents from the Bureau of Alcohol, Tobacco, Firearms and Explosives combed the house for evidence.

Dozens of metal and cardboard boxes filled with ammunition for shotguns, small handguns and assault rifles sat in a driveway. Two of the assault rifles were illegal, Zamora said.

The man had no permit for 75 pounds of black gunpowder that was also recovered, Zamora said.

No arrests had been made. The man, whose identity was not released, was taken to a hospital where he will receive a psychological evaluation, Zamora said.

Last April, authorities said they found more than 1,300 weapons and 89,000 rounds of ammunition in the San Bernardino County home of a man who claimed to belong to a militant group with aims to overthrow Cuban dictator Fidel Castro. Robert Ferro of Upland faces counts of unlawfully owning and failing to register guns