Tucson’s electrical power distribution system has been severely damaged by a fire, prompting the evacuation of the city’s public schools and a postponement of the start of summer school for nearly 200,000 students. 

The power outage began about 1.30pm on Thursday when a transformer exploded and fire broke out in a storage shed, said Rene Feltzer, the chief executive of Tucson Electric Cooperative.

“We’re working to get the power back on and then we’ll try to get students back in the schools,” Feltler told AFP news agency.

Tucson Mayor Kevin Faulconer said he was informed about the fire around 6.30am local time and advised that schools would be closed.

He urged people to avoid the area and to stay indoors and “avoid any exposure to smoke”.

“We don’t want to see any more deaths or injuries,” he said.

The power plant, which provides power to about 15,000 homes, is one of the biggest in the state, and it was the only one of its kind in the country when it was built in the early 20th century.

Its main substation was built during World War II. 

However, since then, power plants in other parts of the US have been damaged or have gone out for days at a time.

Power supply was restored on Friday.

A number of substations in southern Arizona were damaged during the blaze. 

It is unclear if any of the other power stations are also affected.TUCSON HAS BEEN COVERED BY SEVERE WEATHERSTORS  The fire is also affecting more than 3,000 customers in the Phoenix metro area.

Tucotans are still reeling from the power outage and the loss of schools for more than two weeks.

“It’s a devastating situation and it’s going to be a long time before things come back to normal,” said Arizona State University computer science professor Brian McBride.

Students are still being advised to avoid outdoors and avoid crowds in the city.