An EMS worker was killed in a two-vehicle crash west of McLennan, Alta., Monday morning.

A truck hauling empty propane tanks was eastbound on Highway 2 around 11 a.m. when the trailer separated, crossed the centre line and struck a westbound Alberta Health Services ambulance.

The EMS worker, who was driving the ambulance, died at the scene. A second EMS staff member, a patient and a family member sustained non-life threatening injuries. They were all taken to hospital in stable condition.

Sue Conroy, the senior vice-president for EMS with Alberta Health Services, extended condolences to those who were affected by the worker's death. 

"Our immediate concern is to support family and friends and staff in this way that we can and we're doing that," she said. "As you can imagine, from a staff perspective, it's extremely difficult to lose a colleague."

Alberta Health Services sent out a message to EMS staff across the province. EMS stations will lower their flags to half-mast to honour the worker who died.

"The employee involved in this case has been with EMS for many years," Conroy said.

Police released no further details about the crash. McLennan is about 440 kilometres northwest of Edmonton.