Police are looking for a suspect they believe is responsible for a series of TTC collector booth robberies, including one that occurred Sunday night at an east-end station.

A man armed with a black handgun held up the collector booth just before 10:30 p.m. at Chester Station before running off with a quantity of cash.

The TTC employee was not injured.

It’s the second time in three months that Chester station has been robbed -- on Aug. 6, a man stole cash and metropasses during another holdup. Police believe the same man also held up Christie station later that month.

Police say the suspect’s description is consistent for each robbery.

“This is brazen, bold and almost a slap in the face to the TTC and the police,” said Stf. Insp. Mike Earl told reporters Monday.

TTC CEO Andy Byford said he’s determined to help catch the individual.

“We will leave no stone unturned in working with the police to catch this person and to bring him to justice,” he told CTV Toronto. “It’s just outrageous that they think that they can just attack our stations and hold up our staff and steal our funds with impunity.”

Byford said he is concerned the suspect will continue robbing unless he is stopped.

Police say the robberies were well thought out.

Located on the Bloor-Danforth line, Chester Station is an easy target, as it is quiet at night and there are several escape routes.

To beef up safety, the TTC is asking Toronto police to bring back TTC special constables, and Byford said he is taking additional measures to ensure the safety of staff and passengers.

The suspect is described as white, 25-30 years old, 5-foot-10, and last seen wearing dark clothing, a paisley bandanna and a white glove with a grey palm.