An underground fire sent five manhole covers flying into the air, spewed smoke into the streets, and shattered windows near the Port Authority Bus Terminal in Manhattan during yesterday’s evening commuter rush, police and power company officials said. There were no injuries, the fire department said.

The fire, which was initially reported to be in an electrical transformer, was not related to any underground electrical system, Consolidated Edison power company spokeswoman Brenda Perez said. Pressure and gas from the fire caused the manhole covers to blow off, she said. People in the area said they initially worried that the booming sounds were part of a terrorist attack.

“We had no idea what it was,” said James Hall, 35, who was working in a storefront laboratory on 38th Street between Eighth and Ninth Avenues, two blocks from the bus terminal. Mr. Hall said he heard three explosions. “It sounded like a huge metal plate falling,” he said.

Mr. Hall said the first manhole cover blew off under a FedEx truck and he saw the driver run away. He also said windows in his storefront and a nearby Mexican restaurant shattered.

The cause of the fire wasn’t known.