(CNN) -- Police in Northern Ireland said Saturday they were looking for a person on a bicycle who threw a bomb at police officers, wounding three of them.

The cyclist threw the bomb Friday night as police were investigating a robbery at a betting agent in Belfast, police said. The bomb exploded on a sidewalk and the officers were hit by flying debris.

One of the officers remained in a hospital Saturday with injuries to his arm, a spokesman for the Police Service of Northern Ireland said. Another officer was released from the hospital and another, who was not admitted to a hospital, suffered a hearing injury and shock.

The attack happened a day after a report described a sharp rise in dissident bomb attacks, many of which target members of the police or security forces.

The report said the number of devices deployed in the past six months was roughly double that of the previous six months, and the number of devices that detonated in the same period had risen nearly fourfold.

It was written by the Independent Monitoring Commission, a government-created independent panel that looked at the paramilitary and security situation in Northern Ireland.

No one died from the bombs during the half-year period in the report and no one has suffered life-threatening injuries, but the commission warned that the bombs were intended to kill. It said actions by police, and cooperation with police across the border in the Republic of Ireland, was the reason the number of deaths and injuries wasn't higher.