Police have praised the efforts of officers and the community as "heroic" after four men - including a policeman - were stabbed at a mosque.
They were stabbed with a large combat knife by a fellow worshipper inside the Washwood Heath Muslim Centre in the Ward End area of east Birmingham on Saturday night.
A group of worshippers confronted the attacker, who is not known to the mosque, before police arrived minutes later at around 11pm.
One officer used a taser on the suspect but it failed to have an effect on him, said Chief Superintendent Alex Murray. The policeman was knifed in the chest and stomach, around his stab-proof vest.
Chief Supt Murray said: "The work of those officers was heroic and the work of some of the people in the mosque assisting those officers was also heroic."
A 32-year-old man, believed to be of Somali origin, has been arrested on suspicion of attempted murder. He has been taken to a secure mental health facility, West Midlands Police said.
Reports suggest an argument may have broken out between members inside the building prior to the attack. Police said there was no information to suggest it was a hate crime.
Witness Arshad Mahmood told Sky News: "Everyone was frightened you know, it was so sudden and he had a proper knife with him.
"A few of us we went to stop him, one of the guys was strong enough to stop him. Then I held his hand - the guy who also tried to stop him had an injury on his thigh.
"After a few minutes, a police officer came and he also attacked the police officer."
Some of the injuries were serious, though the victims were reported to be in a stable condition.
One worshipper was stabbed in the arm and one in the leg, while another was slightly hurt.
Mohammed Shafiq, the leader of national Muslim organisation the Ramadhan Foundation, said a nearby resident overheard an argument coming from inside the mosque and believes it followed a dispute between members.
He said: "I have spoken to someone who lives a few doors down from the mosque and they described hearing an argument between some of the people inside the mosque.
"It escalated into violence and a police officer has been stabbed."
Mr Shafiq said: "People, anti-Muslim extremists, are going to try to take advantage of this - it's very serious that a police officer has been stabbed during duty.
"The aftermath of the brutal murder of Lee Rigby has led to an increase of attacks.
"The involvement of a police officer in this incident obviously causes more concern."
Officers were conducting patrols in the area in a bid to reassure local people. A cordon is in place while investigations continue at the mosque.
Chief Supt Murray told reporters: "There’s no connection with any other incidents that we can see at the moment, for example Woolwich or any other incidents around the country but we are exploring all lines of inquiry."
A number of mosques have been targeted since the murder of Drummer Lee Rigby close to his barracks in Woolwich, south London, last month.
The killing also sparked a large increase in anti-Muslim incidents in the days that followed, according to the organisation Faith Matters, which works to reduce extremism.
In what were believed to be reprisal attacks, the Islamic Somali Community Centre in Muswell Hill, north London, was burnt to the ground while the Grimsby Islamic Cultural Centre was also targeted by arsonists who threw petrol bombs.