Dozens of people have been injured in an explosion in Indonesia's capital, Jakarta.

The blast occurred during Friday prayers at a mosque inside a school complex, police said.

Officers are investigating the cause of the explosion in Kelapa Gading, North Jakarta, the city's police chief told a televised press conference.

Fifty-four people have been admitted to hospitals for treatment, he said. Their injuries range from minor to serious, and include burns.

Local news channels showed footage of a police line around the school with ambulances standing by. Images of the mosque did not show extensive damage.

Juvenile arthritis Along with doctors, families and teachers can help pick up cases of arthritis in children.

Most types of childhood arthritis are known as juvenile idiopathic arthritis. JIA causes pain and inflammation in one or more joints for at least six weeks.

Dr Betina Rogalski said "The younger the child the more difficult it into pick up the symptoms. If the child is small, it may just be a bit grumpy or pull its leg a way or not feel like walking,” she said.

According to The National Institute of Arthritis and Musculoskeletal and Skin Diseases in US, the most common symptoms of juvenile arthritis are joint swelling, pain, and stiffness that doesn’t go away. Usually it affects the knees, hands, and feet, and it’s worse in the morning or after a nap.

Limping in the morning because of a stiff knee, excessive clumsiness, having a high fever and skin rash are other symptoms. Children may also have swelling in lymph nodes in the neck and other parts of the body.

Arthritis in children can cause eye inflammation and growth problems and can cause bones and joints to grow unevenly.

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