- Video report by ITV News Correspondent Ben Chapman
Five mosques in Birmingham had windows smashed with sledgehammers overnight, in what appears to be a coordinated string of vandalism attacks.
Detectives said the attacks were being treated as linked, and said forensic teams and counter-terrorism officers were involved in the investigation.
Officers were first called at 2.32am on Thursday to reports of a man using a sledgehammer to attack a mosque in Birchfield Road, in the Aston area of the city.
A second report of an attack on a mosque in Slade Road, Erdington, was made at 3.14am.
- ITV News has obtained CCTV footage of what appears to be one of the attacks:
Patrols were then dispatched to areas with mosques and more damage was discovered at buildings in Witton Road, Aston, and in Broadway, Perry Barr.
Reports of broken windows at the Mosque and Muslim Community Centre in Albert Road, Aston, then emerged on social media later on.
West Midlands Police said forensic officers were working on evidence, with CCTV from the areas surrounding the mosques being examined.
Ch Cons Dave Thompson said the motive for the attacks was not yet known.
"What I can say is that the force and the Counter Terrorism Unit are working side-by-side to find whoever is responsible," he added.
Ch Cons Thompson said that since the terrorist massacre in Christchurch, New Zealand, the force had been working with faith partners to provide reassurance and support at mosques, churches and other places of worship across the region.
"At difficult times like this, it is incredibly important that everyone unites against those who seek to create discord, uncertainty and fear in our communities," he added.
But people within the local communities surrounding the mosques said it was a "very worrying" time.
Jawad Khan, from the Birmingham Council of Mosques, told ITV News that there was a "very small element of society" which believed it was acceptable to carry out this kind of attack.
"This is what's worrying to us," he said.
The attacks were condemned as "shocking" and "disturbing" by local councillors.
Labour councillor Jayne Francis tweeted: "Really disturbing to learn of Birmingham mosques being subject to attack. This city is built on tolerance and mutual respect - let's not lose sight of that."
And Birmingham City Council cabinet member Waseem Jaffar wrote: "Deeply shocking and concerning to learn about the attacks on Masjid's [sic] in neighbouring Aston and Erdington neighbourhoods...
"We will not let a very small minority divide our neighbourhood, the city and society and will fight back against any hate and division with love, peace and harmony."
Home Secretary Sajid Javid added his voice to those condemning the attacks, calling the attacks "deeply concerning and distressing".
"[Police] are investigating motive but let me be clear - hateful behaviour has absolutely no place in our society and will never be accepted," he added.
Witnesses or anyone with information are being urged to contact police.