Four mosques in the central English city of Birmingham have been attacked overnight, with a man wielding a sledgehammer seen smashing windows at two places of worship, the police said on Thursday.
Counter-terrorism officers are investigating attacks on the mosques in four different areas in the north of the city, West Midlands Police said in a statement.
The force added the incidents "are being treated as linked".
"At the moment we don't know the motive for last night's attacks," said Chief Constable Dave Thompson in a statement.
"What I can say is that the force and the counter terrorism unit are working side-by-side to find whoever is responsible."