LOS ANGELES  -- 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 with tinted windows at two of the three crime scenes in the San Fernando Valley area Sunday morning, said Sgt. Frank Preciado, a police spokesman.

While the victims appeared to be randomly targeted, investigators determined that the same type of weapon was used in the attacks and the suspect shot at victims from inside a car, he said.

The shootings triggered an intense investigation and prompted the Los Angeles Police Department and Los Angeles County Sheriff's Department to step up patrols on the street.

"It's a major threat," Preciado said.

He urged people to be vigilant until the suspects are apprehended.

"If you see someone that matches that description or their vehicle matches that description, then go off to an adjacent street," he said. "Get away."

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. The family had pulled over after noticing the suspect driving erratically when they were shot, Preciado said.

A woman in her 20s was killed, her mother and father were critically wounded and two children sustained minor injuries from either bullet projectiles or broken glass, Preciado said.

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

Then 15 minutes later and less than 5 miles (8 kilometers) away, a woman in her late 50s who was sitting in a parked car by a church was shot in the head. Preciado said she may have been waiting for someone, but he didn't have more details.

The shootings took place in the San Fernando Valley, about 30 miles (48 kilometers) north of downtown Los Angeles.

Preciado said investigators were pursuing several leads and were looking into whether Sunday's attacks were related to at least two shootings earlier in the week.

"We're not going to be narrow-minded. We're actually going to look at all cases that are similar," he said.

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