LOS ANGELES (AP) — Three people killed and four others injured within the span of an hour Sunday in the northern suburbs of Los Angeles were victims of random attacks that may have been carried out by the same gunmen, police said.

Witnesses spotted two men in a tan- or gold-colored SUV at two of the three crime scenes in the San Fernando Valley area Sunday morning, Sgt. Frank Preciado, a police spokesman, said.

While the victims appeared to be randomly targeted, investigators determined that the same type of weapon was used in the attacks and the manner of the shootings seems to be similar, he said.

“It’s a major threat,” he said.

The Los Angeles Police Department committed a lot of resources to investigate the shootings, he said, and added that authorities were releasing information about them in hopes of getting the public’s help in finding the suspects.

In the first attack, a family of five riding in a car to attend church was struck by gunfire at 5:50 a.m. in San Fernando. Preciado said a 20-year-old woman was killed. Four others were injured; one of them was hospitalized in grave condition.

About 40 minutes later, a man was fatally shot at a Sylmar park.

Then 15 minutes later and less than 5 miles away, a woman in her 50s was found dead with a gunshot wound to the head.

The shootings took place in the San Fernando Valley, about 30 miles north of downtown Los Angeles.

Preciado said investigators were looking into whether Sunday’s attacks were related to at least one other shooting earlier in the week.