TAMPA, Fla. (NBC News) -- A potential serial killer may have murdered a fourth victim early Tuesday, escalating tensions in a Florida neighborhood already on edge.
The victim, 60-year-old Ronald Felton, was fatally shot just blocks from a memorial honoring three people who were killed within days of one another in the neighborhood of Seminole Heights in Tampa.
Tampa Police Department Public Information Officer Steve Hegarty told NBC News it is not known if the death is connected to the three October murders, but said it will be treated as such until authorities can rule it out.
As police scoured the area for a suspect, residents were told to lock their doors and stay in place.
"We need folks to think about everything they heard last night and everything the saw this morning," Tampa Mayor Bob Buckhorn said Tuesday morning during a news conference. "We need to catch this killer before we have to notify one more family that their loved one is dead."
At approximately 5 a.m. Tuesday, police patrolling the area received a call of shots fired and were at the scene within a minute, police said.
A massive police presence descended on the neighborhood, and as of 7:30 a.m., many streets had been closed, according to NBC News affiliate WFLA.
Interim Tampa Police Chief Brian Dugan said police believed the suspect was still in the neighborhood and that officers were knocking on doors in addition to deploying K-9 units and helicopter searches.
Dugan also urged Tampa residents who own firearms to ensure they know where their guns are.
"If you own a firearm of any type, we need you to verify that it’s where it needs to be," Dugan said.
Police have already knocked on approximately 1,900 doors in an attempt to gather information about the slayings, Dugan said.
The first killing took place Oct. 9 when Benjamin Mitchell, 22, was shot in Seminole Heights while waiting for a bus.
Monica Hoffa, 32, was found dead in a vacant lot Oct. 13 after being shot.
While walking Oct. 19, Anthony Naiboa, 20, was shot and killed.
Investigators have not said what evidence ties the three initial crimes together or whether they have forensics that show the same weapon was used in all of them.
"There's some psycho out there putting other people through this pain and suffering I'm going through," Kenny Hoffa, Monica Hoffa's father, said in late October. ""I don't know why he feels the need to go out and senselessly murder people in the street, shoot them down like they're dogs."
Police have released video of a person of interest running during the night of the first murder. Although he is not thought to be a suspect, officials believe the person of interest might have been within range of the murder.
"We believe he may have seen something or heard something that could assist us in this investigation," Dugan said on Oct. 26.
Authorities are offering a $41,000 reward for anyone who has information leading to the arrest of a suspect.
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