HOUSTON -

Authorities are investigating a string of armed robberies at three Denny’s restaurants across the Houston area. Police said they don’t believe the same people committed all three robberies.

The first robbery happened at around midnight near Wilcrest and the Katy Freeway. Investigators said two men in white hoodies ran inside demanding cash.

"I was waiting for my bill to come. They came running in, and one of them had a weapon," said customer Dale Hayden. "As soon as he approached me, that’s when I jumped up after him and chased him outside."

Investigators said the robbers stole cash from the register. They didn’t try to rob any customers but they pistol-whipped Hayden when he tried to stop them.

The second incident happened at around 1 a.m. at the Denny’s on Southmore Boulevard near Highway 288. Three armed robbers walked inside the restaurant and held employees at gunpoint, police said.

"It was a terrifying night for us," said employee Olivia Johnson. "We were scared and we were crying in the back of the storage room."

Johnson said she heard the crooks telling her manager to give them the money. Investigators said the trio stole cash from the register then ran outside and stole cellphones from two customers.

Witnesses told police that the suspects fled the scene in a dark-colored vehicle.

The last robbery happened just before 4 a.m. at the Denny’s near Wilson Road and Beltway 8. Detectives said three armed men got away with an undisclosed amount of cash. No one was hurt.

In response to the rash of robberies, Houston Police Chief Charles McClelland announced his department is working on setting up a multi-agency task force. The officers will come up with a plan to catch and arrest the suspects responsible for the late-night robberies.

Denny’s isn’t the only late-night restaurant being targeted by robbers. In the last month, armed gunmen have hit five Houston area IHOPs. All of those incidents also happened between midnight and 4 a.m. No word yet if those five incidents are connected.