A crash involving an ambulance near Souris in southwest Manitoba killed one man and seriously injured three others, including two paramedics on Thursday evening.

At the time of the collision, the ambulance was transporting a patient in a non-emergency call from Melita to Brandon.

The ambulance was heading north on PR 250 near Souris around 6 p.m.

Witnesses suggested it appeared the driver of a southbound car crossed the centre line and collided with the ambulance. The 54-year-old driver of the car was pronounced dead at the scene.

The road was temporarily closed while crews responded.

"A police car pulled up beside us and just informed us we had to turn around, go back, because there's been a fatal accident," said Kevin Bowie, who was driving in the area near the crash.

Two paramedics and a patient in the ambulance were rushed to hospital with serious injuries from the collision.

"The driver of the ambulance has been admitted to surgical ICU at Health Sciences (in Winnipeg). He is in guarded condition and his family is with him," said Louise Stitt from the Assiniboine Regional Health Authority.

The health authority said the paramedic who was driving is from Melita and has many years of experience as a paramedic.

"We're supposed to be the helpers not those that are in need of the help and I think we probably put up that armour a little bit higher because we know it's going to be tougher dealing with people that you know and your comrades," said Stitt.

The second paramedic has been released from hospital. The patient who was being transported prior to the crash is now listed in stable condition, said health officials.

Paramedics have faced a difficult week. On Monday night, a Winnipeg paramedic was injured after being hit by a suspected drunk driver.

The paramedic was attending to the victim of an earlier crash at Stafford Street and Corydon Avenue.

Paramedics said Friday that increases to the number of calls they're responding to are putting them at greater risk.

Manitoba Health said that in 2008, rural paramedics made more than 63,000 trips.

In 2010, that number increased to more than 71,000 trips.

"More call volumes means we are on the highways, we're on the roads than we've ever been, so we're more exposed to collisions for sure," said Jodi Possia from the Paramedics Association of Manitoba.

The association said those that sign up for the job take defensive-driving courses.

RCMP continue to investigate the cause of the crash near Souris but said speed and alcohol are not considered factors.

- with a report from CTV's Josh Crabb