Police believe the man who shot a Toronto Transit Commission ticket clerk on Sunday night held up the same subway station twice before.

The TTC has "very good" images related to the shooting of the fare collector at Dupont station, the interim head of the transit agency says.

At a news conference Monday, police did not release images of the latest holdup but showed images from incidents in June and October. They said that in all three cases, a heavyset man whose face was covered approached the ticket booth carrying a satchel.

Staff Insp. Mike Earl said that on Sunday, the man pointed a gun at the victim and threatened to shoot him if he didn't hand over the money. When he didn't get any money, he began to walk away, then turned around, "cowardly firing three shots through the glass, two of them striking the victim," Earl said.

The man fled the subway station and was chased by a witness north on Spadina Avenue.

Police ask for help from witnesses

Earl said he hopes witnesses will come forward to provide more descriptions, including the direction the robber fled.

In the first two incidents at the station, the man did not commit any acts of violence but got away with a small amount of cash each time.

He is described as white, heavy-set and 35 to 50 years old, with no apparent accent.

Earl said the man dressed in similar clothing all three times and used the same gun. Police are not aware of the man taking part in any robberies outside the subway station.

Andy Byford, the TTC's chief operating officer, said security tools at Dupont station worked well on Sunday.

"The closed-circuit TV was working," he said. "The alarm was working. Our member of staff activated that alarm. And we've got very, very good imagery from the CCTV images, and obviously we've handed those over to police."

The employee, who was shot twice in the shoulder and neck during the robbery attempt, underwent surgery after being rushed from the station to St. Michael's Hospital. He is expected to make a full recovery.

Byford said the employee is in his mid-50s and has been with the TTC for about 10 years.

Byford said there will be high-profile policing in the transit system over the next few days to reassure customers.

'Outrageous' attack

TTC senior staff met this morning to review what happened, then held a news conference where Byford called the attack "outrageous."

"It's only right that we should at least consider, 'Is there anything more that we can do?' And that's why I've met with our senior management team."

Byford said the employee was on the job and in his booth when he was attacked. The COO said they will look at the design of the glass, which isn't bulletproof.

Byford said he's been talking to individual fare collectors to reassure them and also to stress that they should put their own safety and security first.

"We'd certainly rather lose the cash than an employee," he said.

Coun. Doug Ford, the brother of Mayor Rob Ford, told reporters his thoughts and prayers were with the man's family.

He also said he would like to see the TTC run with no collectors.

"Ultimately, what I'd like to see is — how many of you have been to New York? — there isn't any collectors. You use your pass or your card."

Mayor Ford had similar comments, calling the shooting "terrible" and saying his brother's suggestion was "an idea, we'd have to look at that and see if it's feasible."

Byford said the TTC will inevitably will move toward a system where there is less cash, but that it won't make any rash moves.

"I don't want to knee-jerk into anything because we might otherwise inadvertently introduce another risk or decimate customer service," he said.