BRENTWOOD -- Police are asking citizens to be on guard after a group of suspects used a gun and pepper spray to pull off five armed robberies in little more than an hour Thursday night.

The robberies happened between 8:18 p.m. and 9:35 p.m. at various locations all within the city, Brentwood police Sgt. Walter O'Grodnick said.

The first robbery happened in the north parking lot of the Streets of Brentwood, a collection of stores the 2500 block of Sand Creek Road. That one involved two suspects, O'Grodnick said.

From there, four more robberies involving at least four or five suspects took place, starting at the corner of Presidio and Roundhill drives at 9:15 p.m.

The next one occurred at the corner of Balfour Road and West Country Club Drive at 9:20 p.m.; another on the 300 block of Essex Drive at 9:25 p.m.; and the last one on the 800 block of Minnesota Avenue around 9:30 p.m.

O'Grodnick said the robbers used a black handgun in all of confrontations and in two of the robberies, they also sprayed victims with pepper spray.

The suspects were all described as being either teenagers or men in their early 20s. They were dressed in dark clothing and dark hooded sweatshirts.

Witnesses told police a black two- or four-door sedan was seen after two of the robberies.

None of the victims was seriously injured, O'Grodnick said. They were robbed of cell phones and other personal belongings, he said.

Police urged anyone with information to call Det. George Aguirre at 925-809-7726 during regular business hours or 925-778-2441 after regular business hours.

Contact Rick Hurd at 925-945-4789 and follow him at Twitter.com/3rdERH.