The actions of a 27-year old woman who allegedly arrived on Parliament Hill in a stolen taxi and slipped through two layers of RCMP security before driving away in a second stolen vehicle are raising serious concerns about safety, and dredging up painful memories of the deadly attack that took place there in 2014.

Ottawa police detained a suspect, whom they say has mental health issues. She faces two counts of theft under $5,000 and another charge for stealing a cellphone.

Police said the woman abandoned the stolen taxi in front of Parliament Hill on Monday. Wearing a T-shirt in freezing weather, she bypassed two security checks before attempting to enter Centre Block by claiming to work inside.

Parliamentary Protective Service officers denied her access because she lacked the proper identification. Police said she then jumped in an unoccupied idling vehicle and started to drive off. When the officers realized what was happening, they stopped the vehicle and arrested her at the lower exit of the Hill.

The woman, who is in fact a government employee, has been referred for a mental health evaluation.

Police said she posed no threat to public safety. Parliament Hill is currently quieter than usual: the House of Commons and Senate are on a weeklong break.

But some are now saying the incident does not reflect well on the state of security, particularly in an era when cars and trucks have been used as deadly weapons on unsuspecting crowds.

“It’s been a real security threat in Europe twice in the last year, that means we will probably see some attempt it here in Canada," said security expert John Thompson. “There shouldn’t have been a vehicle left idling and unattended.”

Last July, a 19-tonne cargo truck was deliberately driven into crowds celebrating Bastille Day on the Promenade des Anglais in Nice, France, resulting in the deaths of 86 people. Twelve were killed at a Berlin Christmas market in December after a man drove a large truck into the festival crowd.

Security has been beefed up on Parliament Hill since Cpl. Nathan Cirillo was fatally shot at the National War Memorial Oct. 22, 2014 by a gunman who arrived in a stolen car.

Michael Zihaf-Bibeau then stormed through Centre Block armed with a hunting rifle. He was gunned down by parliamentary security guards, RCMP officers, and then sergeant-at-arms Kevin Vickers.

An estimated three million people visit Parliament Hill every year, in addition to those that work for the federal government. Finding a balance between security and the famously open nature of the Parliament Hill remains a challenge.

The RCMP is constantly working to plug security holes. RCMP officers are now more heavily armed, surveillance has increased and security services have been merged.

But former and current frontline officers on the Hill told CTV News they remain concerned about vulnerabilities that could be exploited, say more vigilance is needed.

“I don't think we're at the point where we're going to stop people from walking up the lawn of Parliament Hill,” said Chris Lewis, former OPP commissioner. “When the time comes, it's a sad day for Canada and we're not there yet in my mind.”

With a report from CTV’s Mercedes Stephenson in Ottawa