An overnight fire destroyed two specially crafted ambulances designed to fit under the numerous bridges and tunnels throughout Central Park, endangering crews' ability to respond to potential emergencies.

The ambulances belong to the Central Park Medical Unit -- a group of 150 volunteers who combat rugged terrain, winding roads and hidden crevices to protect the 35 million people who visit the park each year.

Regular ambulances are too big to fit under all Central Park's tunnels and bridge overpasses, and custom-made vehicles have drastically cut down the time it takes to respond to an emergency in the park.

In 1975, for example, authorities say the average response time was 45 minutes to an hour and a half. Now, the Central Park Medical Unit responds in an average of three minutes.

Garry Resnick, a member of the Central Park Medical Unit, says the group was intended to be a supplement for 911 ambulance services, not a replacement.

But "in a matter of life and death, it really spells a difference," he said.

The fire at a 108th Street parking garage where the ambulances were kept is under investigation. Fire officials say it escalated to two alarms and took about two hours to get under control.

Five firefighters were taken to hospitals with minor injuries.

The all-volunteer Central Park Medical Unit is hoping donations will help replace the destroyed rigs. Each of the units and the gear inside, which included stretchers, defibrillators, soft goods and bunker gear, were worth about $200,000.

"When it comes to transportation, the ambulances are crucial and they need to be replaced as soon as humanly possible," he said.

Donations may be made at CPMU.com.