(NewsNation) — A suspected serial killer is believed to be responsible for five murders since April 2021 in the California cities of Oakland and Stockton. Police say the killer lurks in the shadows and possibly scouts locations to kill before acting.

Kevin Lincoln, mayor of Stockton, said the four killings in his town are “terrorizing” Stockton.

“There’s an unknown individual out there that’s wreaking havoc and it has to stop,” Lincoln said. “We have to do everything we can to catch this individual or individuals, and that’s what we’re doing right now.”

Lincoln said police have established a task force to find the killer and said it is imperative for anyone with any information to come forward.

“Our officers, our task force, is working around the clock right now to bring some sort of resolution and some sort of answers to the families that have been impacted by this senseless act of gun violence,” Lincoln said. “It’s spanned beyond Stockton, it’s been in Oakland as well, so my deepest condolences to the families in Oakland, the mayor in Oakland and the entire city.”

Police have been receiving “well over” 100 tips a day, Lincoln said, a sign the community is anxious to put these gruesome killings behind them.

“This is a tragedy for our community, this has been a very difficult time and our families are grieving right now,” Lincoln said.

While the killer is still on the loose, Lincoln said residents must use extra caution when they’re out, especially at night.

“We will get through this together, but we can’t get through this without your help,” Lincoln said. “So, it is absolutely critical we support each other, that we travel in pairs, we’re in light, well-lit areas and we do everything we can to keep each other safe.”