BERLIN, Jan. 6 (Xinhua) -- Thousands of households, as well as supermarkets, shops, restaurants and other businesses in southwest Berlin, still remained without power on Tuesday, as crew continued repairs to restore electricity after an attack on the grid left parts of the German capital in the dark for a fourth consecutive day.
As of 12:45 p.m. local time (1145 GMT), around 24,700 households and 1,120 businesses in the neighborhoods of Nikolassee, Zehlendorf, Wannsee and Lichterfelde were still affected, Stromnetz Berlin said. The operator predicted full restoration Thursday afternoon because repairs were technically complex.
About 45,000 households and more than 2,200 businesses lost power early Saturday after cables leading to a power station were set ablaze.
Stromnetz Berlin said the five hospitals in the affected districts have been reconnected since the early hours of Sunday.
Residents, however, continued to face freezing indoor temperatures as snow and low temperatures gripped the capital. Christiane, a Nikolassee resident, said her apartment thermometer read 11.5 degrees Celsius. "It's well known that you should sleep in a slightly cooler environment," she said. "But this cold?"
A group calling itself Vulkangruppe (Volcano Group) posted a statement online on Sunday claiming responsibility, saying it had "successfully sabotaged" infrastructure linked to a gas power station in Lichterfelde.
Berlin's governing mayor, Kai Wegner, described the incident as "a terrorist act" at a news conference on Tuesday.
"We have experienced a terrorist attack in this city," said Wegner said. "A left-wing terrorist attack. I want to reiterate: This was not a minor arson attack, nor was it sabotage. This was a terrorist act."
Germany's Federal Prosecutor's Office is investigating the case on suspicion of terrorism, German news agency dpa reported on Tuesday. The authority said it suspects offense including membership in a terrorist organization, unconstitutional sabotage, arson and disruption of public services.
Berlin Interior Senator Iris Spranger welcomed the federal takeover of the probe. "We are talking about a left-wing terrorist attack on our power grid, meticulously planned and carried out with considerable criminal intent," Spranger said.
