It's five o'clock on a Friday afternoon and not a single ambulance is available in the city.

Thousands of commuters are on their way home or to the cottage. The thermometer is hovering around 30 C. It's a peak time for emergency calls, but nobody can respond.

Five paramedics have called in sick. There are eleven ambulances on the street and they're all busy on calls. Two of them are sitting at St. Joseph's Hospital waiting for their patients to be unloaded.

At the Hamilton Emergency Medical Services headquarters on Victoria Avenue North, supervisors are on the phone with dispatch, jump-starting their emergency plans.

Ambulances are called in from Caledonia, Halton and Cambridge. Patient transfers are delayed.

A senior official calls the hospital to ask for the two patients lying on stretchers to be swiftly admitted.

As each minute ticks by, the tension heightens. They know a new call comes every 10 minutes.

They call it a Code Red, the dangerous moments when the city has zero ambulances available.

Not that long ago, they didn't use the term. The rare occasions when no ambulance was available were anomalies that quickly passed.

Then on May 17, 2006, Hamilton went more than an hour with zero to four vehicles available, a number considered less than safe. For 10 minutes there were none.

The shortage was so unnerving, senior staff invoked the city's emergency plan. Extra paramedics and volunteer firefighters were called in. Hospitals were asked to clear ambulances as soon as possible.

The next day, the issue was front page news.

Other municipalities called Jim Kay, head of fire and emergency medical services, to question all the fuss. Ambulance shortages were no longer emergencies in their communities. They were becoming normal.

It was a grave premonition for Hamilton.

From May to Dec. 12 last year, there were eight Code Reds. Then in the next month, there were 19. Now they're a regular occurrence, about every two weeks.

There aren't any more calls. But more are being upgraded to lights-and-sirens emergencies. Required meal breaks for paramedics are also taking ambulances out of service.

But the main issue for the ambulance team is just a trickle-down of the crisis facing the entire medical system. Supply and demand. There are more patients than beds and medical staff. The backlog travels all the way through the hospital and out the doors to the ambulance bays.