NEW YORK – The chief of the Fire Department of New York's Emergency Medical Service Command has been replaced amid investigations into the city's response to a blizzard that stranded ambulances and created a backlog of more than 1,000 emergency calls.

Abdo Nahmod, who has been overseeing the department's Emergency Medical Dispatch, will take over the post from John Peruggia, who held the top job for six years, Fire Commissioner Salvatore Cassano announced Wednesday.

The city is facing multiple inquiries into its performance during the day-after-Christmas snowstorm that brought much of New York to a grinding halt. Mayor Michael Bloomberg has directed Skip Funk, the citywide director of emergency communications, to examine why the communications and dispatching system failed.

In the days after the blizzard, one woman with a broken ankle waited 30 hours for an ambulance. Another woman waiting for help gave birth to an unconscious child who was declared dead later at the hospital.

Federal prosecutors and city investigators are looking into claims that sanitation workers sabotaged the city's snow cleanup.

"We didn't do the job we had wanted to do, that I wanted to do and everybody else wanted to do," Bloomberg said Wednesday of the storm, adding that the city is preparing for more snow expected this weekend.

Nahmod has supervised Emergency Medical Dispatch for three years. He started out as an ambulance company volunteer, became an emergency medical technician in 1986 and later served as Staten Island borough commander. He earned a master's degree in homeland security studies last year.

"Last week's blizzard presented tremendous challenges for the department that are currently being addressed with an eye toward improving performance going forward," Cassano said in a statement.

While Peruggia provided "dedicated service to this Department, I felt new leadership was needed at this time," Cassano said.

City operators fielded 49,478 calls to 911 on Dec. 27, the day after the storm. That total was the sixth highest in any day since the city began keeping statistics. At one point, there was a backlog of 1,300 calls.