Police cordoned off the crime scene in Herbert Road while specialist police teams carried out forensic investigations.
The incident occurred on Friday night when the boy was dropped off at the Idaara Maarif-e-Islam mosque, commonly known as Hussainia, by his father, who went to park the car.
“It happened on the pavement. By the time the dad parked his car his son was on the floor. There was a young man who was brutally beating the boy with a knife,” Azhar Kiana, the president of the mosque, told local media on Saturday.
“There was blood everywhere, he was hitting the boy’s neck and head. Then the attacker ran off and got into a car.”
The attack was one of several violent incidents in four cities that left two people dead and several others injured on Friday night and the early hours of Saturday.
West Midlands police said a 29-year-old man has been arrested on suspicion of attempted murder on Saturday morning and is in custody.
Police said they were not treating the attack as a terrorist incident but the motivation remained unclear.
It is suspected, however, the incident could have been a racially or religiously motivated hate crime.
“Our investigation is progressing quickly but it is still in the early stages. We do not believe it to be terror-related. The motivation for the attack is not yet known. We are keeping an open mind as to whether it could be racially or religiously motivated,” said DI Jim Colclough from the complex crime investigation team at Bournville Lane police station said.
London’s Metropolitan police recorded more than 1,200 hate crime incidents against Muslim victims from April 2016 to March 2017, pointing to a surge of Islamophobia in the UK.
Last year, a Huffington Post UK poll showed more than half of Britons viewed Islam and Muslims as a threat to the liberal democratic values popular in the United Kingdom.