Military exercises across Southern California have shaken some residents as sounds of gunfire and helicopters have erupted in the middle of the night.

Military helicopters, simulated gunfire and flash grenades rattled Pasadena, Long Beach and other Los Angeles-area suburbs this week — exercises that could reportedly continue in Southern California for years.

Late-night military training exercises shook neighborhoods across Southern California as residents reported hearing helicopters, simulated gunfire and explosions overnight.

The U.S. military was conducting a training exercise in the Long Beach and City of Industry areas Thursday night into Friday morning — a day after similar exercises occurred in the Pasadena and Irvine areas. Long Beach Police Department personnel were in the area Thursday night to assist with pedestrian and vehicle safety, police said.

The first round of noise is expected to begin around dusk, at 8:30 p.m., and the exercises will continue until around 12:30 a.m., according to city spokesperson Lisa Derderian.

While agencies train often, preparations for the several large events coming to Southern California in the next couple of years will result in more exercises, one official said.

A joint military training exercise led by the New Hampshire National Guard will take over the former Loring Air Force Base in Limestone for five days starting next Monday. Half a dozen units will participate in Operation Northern Phoenix,