An explosion inside a hangar -- filled with dangerous chemicals and million-dollar aircraft -- sent people running for safety at Brown Field.

The three-alarm fire caused extensive damage to several buildings at the airport, but one witness said it could have been much worse.

“There’s a lot of airplanes with a lot of fuel in there. The whole thing could have gone up pretty badly,” said Jeffrey Schuster, who owns a hangar near where the fire started.

Schuster said he was driving through the security gate when he heard explosions.

“Flames were coming off the roof, about 500 feet with black smoke. There were multiple explosions. I counted at least six. Blew out my windows (of my hangar,)” he said.

San Diego and Chula Vista firefighters arrived at Brown Field around noon Tuesday. A HAZMAT team was also requested.

“There’s jet fuel, there’s nav gas, there’s profane, there’s nitrogen, everything in those hangars,” Schuster said.

The fire was extinguished by 1:30 p.m. The cause of the fire is under investigation.

At last check, no injuries had been reported, which Schuster sees are a miracle.

“If the fire trucks hadn’t gotten here in time, everything here would have gone up,” he said. “There’s a lot of airplanes in it, and it could have been a real, real nightmare.”

Brown Field, located about one mile north of the U.S.-Mexico border, accommodates private and cargo planes.