JACKSONVILLE, Fla. -

As investigators continue to look into a crime scene that included two robberies and a double hit-and-run that left one man dead Sunday morning, those in the area say they're worried about what happened.

"It concerns us as being administrators and having kids on campus," said Melvin Moore, an administrator at nearby ATCOM Christian School.

Moore said he's about what happened right across the street from the school where he works. It's where police say two people were robbed and one of them hit by a car at a post office near Wesconnett Boulevard and 103rd Street. Minutes later, a bicyclist -- 56-year-old John Sikes -- was hit by a car and killed just a few miles away on La Moya Avenue.

IMAGES: Westside sees 2 crime sprees in 2 days

"Our whole campus is on high alert and lockdown because we do have summer camp going on," Moore said.

Police believe the crime spree started at a bus stop on Wesconnett when two men approached a man sitting down and robbed him. They didn't hurt him. After that, investigators believe that the gunmen went to the post office right behind the bus stop and confronted another man.

That other man -- 58-year-old Dan Ellis, a longtime Duval County Public Schools employee -- told police the men robbed him and hit him with their car, then drove off. Ellis remained in the hospital Monday. His daughter said he's in high spirits despite what happened.

A little while later, not far from the post office, detectives believe the two thieves hit and killed Sikes, a man whose family says went for an early morning bike ride. The crooks left that scene and police say dumped the car at a nearby apartment complex. They're still on the loose.

"These individuals are extremely dangerous," Channel 4 crime analyst Ken Jefferson said.

He said police finding the car involved is a step in the right direction, but now they need the community's help.

Jefferson said if you're ever confronted by armed robbers, don't fight back.

"Don't try to intercede, don't try to take the weapon away, don't try to stop them," he said. "Just give it up, contact the authorities."

Police said this crime spree is not related to a pair of robbery shootings in Avondale early Monday morning.