Investigators in California were working Monday, Dec. 1, to identify one or more suspects who opened fire at a child's birthday party over the weekend, killing four people and injuring 11 others.

The shooting erupted at a banquet hall in Stockton at least 100 people gathered for the celebration, according to San Joaquin County Sheriff Patrick Withrow. He said the incident may have involved more than one shooter and appeared to be targeted, but he did not elaborate.

Three children and one adult were killed in the shooting, the sheriff's office said. The shooting left 11 others injured, and several of them, including multiple children, were taken to local hospitals. Withrow said at least one person remained in critical condition.

Officials have not publicly identified the victims.

After the shooting, the Stockton Police Department said it arrested five people, including one juvenile, on conspiracy, weapons and gang-related charges. It's unclear if the arrests had any connection with the shooting.

Since the deadly attack, which Gov. Gavin Newsom called "horrific," law enforcement officials have asked for the public's help in identifying possible suspects, requesting cell phone video and eye witness accounts.

"We need everyone who has any information on this to reach out to us," Withrow said at a news conference on Sunday, Nov. 30. "This is the time for our community to show that we will not put up with this type of behavior where people will just walk in and kill children."

How the mass shooting at a child's birthday party unfolded

Withrow said authorities first received reports of gunfire at the banquet hall shortly before 6 p.m. on Nov. 29. At the time, as many as 150 people there for a child's birthday party.

Officials said it appears the gunfire started inside the banquet hall before moving outdoors.

Investigators processing the scene viewed multiple cars with bullet holes and retrieved several firearms from the roof of the building, though it's unclear if the weapons were related to the shooting.

Three children – ages 8, 9 and 14 – and a 21-year-old were killed in the shooting, the sheriff's office said.

Stockton Mayor Christina Fugazi said the 8-year-old who was killed was a student in the Stockton Unified School District. She said the child’s parent also works for the school district.

Fugazi also announced that a $25,000 reward was being offered for information leading to the arrest of any suspects.

Vigil held in memory of Stockton shooting victims

Hours after the deadly shooting, hundreds of people gathered for a prayer vigil near the crime scene.

Speaking to the crowd, Stockton Vice Mayor Jason Lee recalled a shooting at an elementary school in the late 1980s that killed five children in Stockton.

“We all remember where we were on that day. I don’t want to have those types of memories over and over again," he said. He added: “That trauma lives on forever, and this community is dealing with a lot of trauma."

After the vigil, family members could be seen removing gifts and other items from the banquet where the shooting occurred. One man who was wearing a birthday-themed T-shirt said he was retrieving his daughter's belongings. He asked the media for privacy.

'This was not a random act'

Withrow said the attack appears targeted, but did not say why investigators believe that.

"We're going to say that we're confident that this was not a random act," Withrow said at a news conference. "They walked into this area and was probably looking for somebody in particular. Why they did that, what they're part of, who they are — we don't know."

Contributing: Victoria Franco, The Stockton Record; Karissa Waddick and Thao Nguyen, USA TODAY

This article originally appeared on USA TODAY: Police search for suspect after 3 children killed at California party

Reporting by Christopher Cann, USA TODAY / USA TODAY

USA TODAY Network via Reuters Connect