All four soldiers had served in Afghanistan.
"There is no question. The government needs to urgently act upon this," said NDP veterans affairs critic Peter Stoffer in an interview with CBC News.
Stoffer said the Conservative government must make immediate changes to the way the military deals with soldiers who have PTSD.
"You admit you have a problem and get diagnosed and the clock starts ticking on your exit out of the military and that adds tremendous stress to the men and women who served."
Stoffer said soldiers with PTSD should be allowed to stay in the military, get the rehabilitation and psychiatric treatment needed and then get the skills training to transition to a civilian job. Only after getting a job should they have to leave the military.
Veterans ombudsman Guy Parent echoed those sentiments before the Senate subcommittee on veterans affairs Wednesday.
"Recent events have tragically shown that for some the uncertainty of their future was such as they perceived there was no hope," he said.
Military ombudsman Pierre Daigle told CBC News Network that a key hurdle to delivering care is a lack of adequate resources.
Daigle said that in 2002, the military identified a need for 147 health-care providers. He said that number was never met.
"So this chronic undermanning is a key issue here," he said.
He added that the government had earmarked more than $11 million to recruit and increase the number of care providers in the military. But he said currently there are 76 fully assessed candidates in a pool waiting to be hired.
"Because of bureaucratic impediments, because of cumbersome and a lengthy hiring process, I'm afraid if they're waiting too long to bring them in, there will be a potential loss of these qualified candidates and there may be further delays," he said.
Military psychiatrist and colonel Dr. Rakesh Jetly told CBC News Network that the Canadian military has the highest ratio of mental health providers to soldiers compared to the country's NATO allies.
"I think our organization probably talks more about mental health, about treatment, about suicide, about stigma than probably any other subsection of Canadian society," he said.
Jetly said one challenge is getting soldiers to self-identify as having mental health issues and come forward for help.
Liberal Leader Justin Trudeau said the government has to do more.
"I think there's a real lack of compassion and coherence in how this government deals with its veterans and its veteran families," he said. "If we're going to send our young men and women into dangerous places, we need to be ready to support them fully when they return home. That should be part of the deal."
In question period Wednesday, Prime Minister Stephen Harper conveyed his condolences to the friends and families of the soldiers.
"I think it's the responsibility of all of us to encourage those who need support those who need help to get that help. We should reach out to them, encourage them to do that. Those supports are available and we'll make sure that they continue to be available," he said.
According to military statistics, there were 10 suicides in 2012, down from 21 in 2011. There were 12 in 2010.Suggest a correction