"Someone out there knows who did this," Phoenix Police Department Chief Joseph Yahner said

Arizona police are looking for a suspected serial killer who may be responsible for fatally shooting at least seven people since March in Phoenix, including a 12-year-old girl, officials announced.

Police released a sketch of the man they suspect to be behind seven homicides and two non-fatal shootings on the city’s west side. The new figure comes after detectives tied four new shootings to a string of unsolved homicides, according to a police statement.

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“Someone out there knows who did this. We need our community to call us or Silent Witness and help us solve these cases, bring justice to these families and victims, and prevent more violence from occurring,” Phoenix Police Department Chief Joseph Yahner said in the statement.

The alleged shooting spree began on March 17, when a 16-year-old boy was shot and wounded while walking down the street at around 11:30 p.m., police said.

One day after the gunman attacked the teen boy, a 21-year-old man was shot and wounded while standing near his car at around 11:30 p.m.

The deceased include: Diego Verdugo-Sanchez, Krystal White, Horacio De Jesus Pena, Manuel Castro Garcia, Angela Linner, Maleah Ellis and Stefanie Ellis.

Police previously said that the gunman drove up to 21-year-old Verdugo-Sanchez, as he stood near a home, and fired several shots at the man from inside a car, ABC 15 reports. The man was taken to a hospital where he later died.

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Castro Garcia, 19, was in his car in front of a friend’s house when the gunman drove up alongside him, police said, according to ABC 15. After a brief conversation, the suspect opened fire, killing Castro Garcia.

The latest of the shootings occurred on June 12, with the deaths of Linner, Maleah and Stefanie Ellis.

Linner, 31, and 12-year-old Maleah were found dead in their car, ABC 15 reports. Maleah’s mother, Stefanie, 33, died later at a hospital. All three suffered gunshot wounds.

A witness reported seeing a suspect leaving the seen in a light-colored vehicle, according to ABC 15.

Police said a witness provided detectives with a sketch of the suspect.

“It’s times like these, when violent predators victimize our fellow citizens, that the cooperative relationship between the community and it’s police department is most crucial,” Yahner said in the statement.

“No fact is too small and no suspicious activity is too slight; if you see something, say something.”

Suspect Is Thin Man in His 20s, Possibly Hispanic: Police

Police are offering a $30,000 reward for information leading to the gunman’s arrest. The suspect has been described as a thin man in his 20s, according to ABC News.

Officials noted that although the man has been described as Hispanic, police are “uncertain so are not stating for sure.”

BreAngela White told NBC News that one of the victims was her 55-year-old mother, Krystal White, who was shot and killed on April 19. The woman was found dead along the side of a rode, according to ABC 15.

“It’s scary just knowing that somebody out there taking innocent lives – someone’s mother, someone’s daughter – for no reason, and nobody has any answers,” she told NBC.