The sudden and severe shortage of ambulances in the Lower Mainland over the weekend was orchestrated, according to B.C. Ambulance Service officials.

Service CEO Lee Doney says paramedics acted irresponsibly by booking off their scheduled shifts mere hours before they were scheduled to work on Friday night and Saturday morning.

"Putting patients at risk is no way to impact your frustration," Doney said. "Two hours before the shift change, 50 paramedics book it off on short notice. Something is orchestrated."

On Saturday, 23 ambulances were out of service in the Lower Mainland, the Fraser Valley and the Sea-to-Sky corridor.

Roughly 100 ambulances normally service the area on Saturdays.

Authorities call it an illegal strike, but the union says paramedics aren't breaking any rules.

Last weekend, the B.C. government legislated an end to the paramedics' seven-month strike and imposed a contract on the 3,500 ambulance workers.

In doing so, paramedic spokesman B.J. Chute says the previously imposed essential services order was voided.

"All overtime became voluntary," Chute said. "Paramedics are choosing on an individual basis not to volunteer for an employer that has treated them so poorly and with such disdain for the past seven months."

According to Chute, paramedics work 12 hour days up to six days a week -- and there are roughly 100 vacant positions in the Lower Mainland alone.

"There's simply not enough paramedics in Vancouver to fill the shifts that exist," Chute said.

"The ambulance service as a cost cutting measure would rather roll the dice and risk those lives than fix the ambulance service."

With files from The Canadian Press and a report from CTV British Columbia's Norma Reid