Updated

Residents of Phoenix's west side are on edge as they wonder if a serial shooter is targeting their neighborhood.

Phoenix police say they are investigating whether the same person is behind four incidents that have killed six people, including a 12-year-old girl, in the city's Maryvale area.

The location, time of day and method of operation are some of the common factors among the slayings, which date back to April 1, Sgt. Jonathan Howard said. He declined to release further details.

Five of the victims died in shootings that occurred in a nine-day period last month. All of them were outside a residence at night when they were killed by gunfire from a vehicle. The crime scenes are within an area between 55th and 67th avenues and McDowell Road and Campbell Avenue.

Police held a forum with the community this week, advising residents to be vigilant and report any suspicious people or vehicles.

Margarito Castro, whose 19-year-old son was among the victims, attended that forum.

"He was a good person," Castro told The Arizona Republic (http://bit.ly/29tNIum). "He didn't have problems with anyone. The detectives looked at his social media, and they said he was a good guy."

Manuel Castro Garcia was sitting in a car outside a house in the area of 65th Avenue and Coronado Road the night of June 10 when, authorities said, a dark sedan pulled up next to him. Witnesses heard the victim and the suspect argue and then shots were fired, according to investigators.

Castro Garcia tried to drive despite being wounded, but he crashed his vehicle a few houses away, police said. He later died at a hospital.

Horacio de Jesus Pena, 32, was also killed in a drive-by shooting while standing outside a residence the night of June 3. Responding officers found in in the roadway with gunshot wounds and pronounced him dead at the scene. One witness reported seeing a white sedan in the road just before shots were fired.

On June 12, police found Angela Linner, 31, and Maleah Ellis, 12, shot to death inside a car outside a home. The girl's 33-year-old mother, Stefanie Ellis, was rushed to a hospital in critical condition. Ellis succumbed to her injuries Thursday.

Authorities now believe an April 1 drive-by shooting was carried out by the same suspect or suspects. Diego Verdugo-Sanchez, 21, was in front of his house around 9 p.m. when an unknown vehicle approached, according to police. Someone then fired shots from inside the car. Verdugo-Sanchez was found with gunshot wounds. He died at a hospital.