Vic woman burnt after basketball explodes

A woman has burns to her face and arms after a basketball she picked up at a Melbourne beach exploded.

The ball exploded in the 21-year-old woman's arms at Black Rock beach about 10.40pm on March 18, police on Tuesday said.

She ran into the water to cool the burns to her face, head and forearms before paramedics arrived and took her to hospital.

The arson squad believes sparklers may have been attached to the ball, which witnesses say was rolled onto the beach by a group of people.

"At this time the reason for the explosion is unknown and police are not sure whether the group had intended for anyone to pick up the ball or why the group had it at the beach," a police spokeswoman said in a statement.