British schoolboy, 8, killed by grenade thrown through flat window during Sweden visit

Yuusuf Warsame, 8, was visiting relatives with his mother, brother and sister

Yuusuf's family said he was in a room with his mother and siblings when a grenade crashed through the window, killing him and wounding two others (Family handout)

An eight-year-old British schoolboy was killed by a grenade while he slept alongside his mother and young sibilings on a family visit to Sweden, in what has been described by police as a “despicable and abhorrent” attack.

Yuusuf Warsame, who was born and raised in Birmingham, had been visiting relatives with his mother, brother and sister.

The explosive was thrown through the window of a third-floor flat in the Biskopsgården suburb of Gothenburg at around 3am on Monday morning, in what police have described as a possible revenge attack within the city's Somali community.

At least five children and several adults were inside at the time, said police. They said Yuusuf suffered serious injuries and later died in hospital.

The child was visiting relatives in the area when the grenade was thrown through a flat window (Getty)

Yuusuf's parents, both Dutch passport holders, moved to the Sparkhill area of Birmingham in 2001.

His father Abdiwahid Warsame told the Birmingham Mail his son had died in the grenade attack, and that he was awaiting more information from the Swedish authorities.

A spokesperson for the family told the newspaper: "The room that Yuusuf was in when the attack happened was also occupied by our mother, sister and youngest brother. It is a miracle none of them were badly injured."

Police spokesperson Thomas Fuxborg told the Swedish edition of The Local that the incident was being investigated as murder, saying the block of flats housed residents with a number of serious criminal convictions.

“It could have ended much worse,” he said.

“Someone was standing outside the apartment and threw a hand grenade through the window, into the living room. The boy was not part of the family registered at the address.

"This is abhorrent. From the outside it is impossible to know who is in the apartment. That it affects an eight-year-old completely innocent boy is despicable,” he added.

Fuxborg said one of the men registered to the address Yuusuf was visiting had been involved in a fatal shooting at the address last year.

He said the two incidents could be linked. “We’ll have to see if the motive is linked to that,” he said. “Our theory is that it may be.”