Series of explosions rock California Oktoberfest celebrations

A series of explosions rocked an Oktoberfest celebration in Huntington Beach, California, injuring five people.

Authorities on Saturday responded to the scene at 8:10 p.m. local time to reports of multiple explosions that caused a transformer fire at the Old World Village complex. The complex had been hosting the Old World Village Oktoberfest festival.

Staff at a festival restaurant noticed an odor coming from an underground vault just outside the facility, Jeff Lopez of the Huntington Beach Fire Department told reporters Sunday. The underground vault contained three transformers but only one exploded. At one point the vault's 50-lb. metal lid flew off during the explosion, Lopez said.

Two firefighters at the scene were injured and treated at a local burn center. Both have been released. A third person is still hospitalized with moderate to severe injuries, Lopez said. Damages to the restaurant were minimal.

The area was immediately evacuated and a HAZMAT team was called on to investigate the explosions.

Witness Kyle Nelson told a local television station that he heard and saw three large explosions in rapid succession coming from the festival, according to the AP.

ABC News' Matt Fuhrman contributed to this report.