The Zimbabwe Broadcasting Corporation (ZBC) said the accident happened Saturday at an agricultural show in the town, 74 kilometres (44 miles) east of Harare.

"The incident occurred when some rifles that were being used by members of the Zimbabwe National Army ... malfunctioned during mock drills using blank ammunition," the radio quoted army headquarters as saying.

The report said that the three serious casualties had been taken to a hospital in the capital Harare.

It did not give any details of the casualties, but the private Standard newspaper said Sunday the injured included civilians and children. The paper quoted an eyewitness claiming a grenade had been thrown.

"Something exploded and there was a stampede. People were screaming, running in all directions," the eyewitness said.

A weapons expert contacted by AFP said the injuries could have been caused by a stun grenade, often used by the army in mock battles.

Contacted for comment, police spokesman Wayne Bvudzijena said he did not have any more details.