Police heightened security Friday around the Austrian capital's around 60 mosques following an explosion last week at a building housing a Muslim prayer center, an official said. Extra officers will patrol areas around Vienna's mosques on Friday, said Gert Zander, an official in the police anti-terrorism department. "We routinely heighten security in sensitive times," he said. No one was injured when a homemade bomb went off early Thursday. The blast blew out windows and heavily damaged the first floor of the building, which housed a Muslim prayer center. It is located next to a mosque and a Turkish-owned business. It was unclear what the explosion targeted and what explosives were used, Zander said.