Police fired in the air and launched tear gas shells to disperse demonstrators in the central city of Multan after they attacked the office of the state electricity company and set fire to a bank, they said.

Television footage showed a furious mob beating several power company employees with wooden planks, setting fire to motorbikes and rampaging through the streets.

Multan is the home city of Prime Minister Yousaf Raza Gilani, a member of the party of slain opposition leader Benazir Bhutto, who took office last month pledging to end shortages of both food and electricity.

“More than 40 people were wounded including 11 power company employees, seven policemen and two television cameramen,” local police officer Mirza Mohammad Ali said.

Witnesses said 21 protesters from local textile factories forced to shut down by the outages lasting several hours were among those injured in the rioting.

Police have detained some 50 people for incidents of violence, Ali said.

Pakistan suffered major outages earlier this year which authorities blamed on a lack of water for hydropower facilities. The country suffers an overall lack of power generating capacity.

In March the country’s biggest city, Karachi, was blacked out when the main power utility accused the local electricity company of refusing to pay a half-billion-dollar bill.