Brann på Fiumicino, Roma

Rome airport fire strands thousands of fliers

Smoke is seen over Rome's Fiumicino international airport where a fire broke out overnight on May 7, 2015. (Photo: TIZIANA FABI, AFP/Getty Images)

Smoke rise from Rome Airport in Fiumicino, A man wears a mask after a fire at the  Fiumicino international airport.

More than 175 flights have been canceled and dozens more delayed at Rome's busy Fiumicino airport Thursday after an overnight fire disrupted operations there. The incident has stranded "thousands" of passengers, according to media reports.

The fire broke out inside the international terminal -- Terminal 3 -- just after midnight local time (6 p.m. ET). It took about five hours to bring under control, according to The Associated Press. The fire, thought to be sparked by an electrical short circuit in a restaurant, spread through about 4,000 square feet of retail space beyond the airport's security checkpoints.

The impact to fliers was significant Thursday. Some departures had resumed by noon local time, but a third of the day's flights had been canceled as of 1 p.m. local time (7 a.m. ET), according to flight-tracking service FlightAware. Airport officials told The Wall Street Journal Fiumicino was "gradually" beginning to resume its schedule, but it was unclear how long significant disruptions might linger.

The international terminal was closed to passengers as of early Thursday afternoon. Flights scheduled to operate from that terminal were being shifted to other parts of the airport.

Overnight, 19 international long-haul flights were permitted to land at the airport early Thursday, but most others were canceled or had to divert.

The Rome airport is Italy's busiest airport, serving about 130,000 passengers a day. It's a hub for Italian carrier Alitalia.