Counter-terror police have been drafted in to help with a major hate crime investigation after a small home-made bomb exploded near a mosque.
Around 150 people were evacuated from their homes in the Caldmore area of Walsall on Saturday night while bomb disposal experts made the device safe.
West Midlands Police said a loud bang heard by residents late on Friday "appeared to be consistent" with the device exploding. No one was injured and it caused minimal damage.
The remains of the device were found in an alleyway adjoining the Aisha Mosque and Islamic Centre in Rutter Street on Saturday by a local man who took them home and showed them to his wife.
The mosque's imam also took them home later before anyone realised their significance.
Assistant Chief Constable Sharon Rowe said last night: "The force is taking this attack against the mosque very seriously and we have a major investigation under way.
"To that end, I have called in support from all over the force, including the West Midlands Counter Terrorism Unit, which has a number of experts supporting the inquiry.
"Specialist investigators have been working all day and continue to ensure that we maximise every opportunity from the crime scene."
She added: "At this stage we are keeping an open mind on a motive, but have recorded it as a hate crime. A hate crime is any criminal act committed against a person or property that is motivated by the offender's hatred of people because of their gender, race, religion, disability or sexual orientation."
Police have stepped up patrols in Walsall to reassure the community, despite believing the planting of the device was an isolated incident.
Zia Ul-Haq, a committee member and spokesman for the mosque, told BBC WM the device was handed in on Saturday evening, and committee members called police at about 10.15pm because it looked suspicious.
He said: "The package was found along the front boundary wall, on the corner of the building. It was found by one of our worshippers who after midday prayer was going home, and he had a look and it looked suspicious, so he picked it up and took it home.
"He showed it his wife and his wife said, 'Well, it looks like something suspicious so you should take it to the mosque'. So he brought it to the mosque but unfortunately there was nobody responsible in the mosque so he took it back home.
"Then he brought it back in the evening and then our imam had a look at it, and he took it home because nobody thought it was that serious."
Eventually, several people, including members of the committee, got together at the mosque and decided to call police after assessing the item, which was reported to contain a battery.
"I said it looks suspicious and we decided to call the police. As soon as the police came they said we should not have handled it."
Mr Ul-Haq thanked the police and the local council for their support following the discovery.
He said: "They have taken this very seriously and they have supported us wholeheartedly and we are very grateful to the police and the local authority.
"We are not suspecting anybody, we are leaving it in the good hands of the police. We have beautiful relationships with the local community and we've never had any trouble at all at our mosque."
Mr Ul-Haq told the BBC that the mosque had been in existence for more than 40 years and had very good relations with communities of all faiths, holding open days for non-Muslims.
"We never ever thought there was going to be a problem and people are still finding it hard that somebody could have targeted us."
Bomb disposal experts from the Royal Logistic Corps attended the scene to ensure the device was safe and forensic teams spent several hours conducting a detailed search for evidence.
About 80 people evacuated from the area as a precautionary measure overnight were given shelter by Walsall Council, while 70 residents stayed with friends or family.
Councillor Zahid Ali, portfolio holder for public health and protection, said: "We stand shoulder to shoulder together as a community in support of the police.
"We've worked very hard with the community and shown that we were there for them when the evacuated residents needed shelter.
"Walsall has really shown its mettle in coming together and responding with calm determination."
It comes after a number of recent incidents at mosques following the murder of Drummer Lee Rigby in Woolwich, London.
Last week two men were charged in relation to an alleged arson at a mosque in Gloucester, and an Islamic cultural centre in Grimsby was hit by petrol bombs last month.
Mosques in Braintree, Essex, and Gillingham, Kent, have also been targeted.