SAN DIEGO — Flames tore through a popular Kearny Mesa restaurant Monday night, causing an explosion, destroying the eatery and badly damaging surrounding businesses.

Shortly after 9:30 p.m., firefighters arrived at China Max Seafood Restaurant, a two-story building on Convoy Street and Engineer Road in the Plaza del Sol strip mall.

The fire started on the first floor, but a build-up of smoke, heat and debris led to an explosion that blew out the restaurant’s windows and spread flames to the second floor. At one point there were about 20 fire engines on scene with crews battling the flames.

Two firefighters suffered minor injuries and no one else was hurt, according to San Diego Fire-Rescue.

The restaurant had been closed to dine-in customers due to the coronavirus pandemic but was open for takeout, so kitchen staff were cooking before the blaze, officials said.

The restaurant was not the only business affected — others suffered major damage, and firefighters determined the building was a “total loss.” Investigators estimated the blaze did $4.5 million in damage, according to City News Service.

The cause of the fire remained under investigation early Tuesday.