Children playing in the water at a park in Lake Ronkonkoma Sunday found a hand grenade that later had to be destroyed by Suffolk police.

Police could not say if the grenade was still live when it was discovered, but did say the pin was intact. The beach was evacuated by Fourth Precinct and Emergency Services Unit officers and police said a robot was used to secure the grenade and place it in a hole, where it was "countercharged" -- or, destroyed -- with a blast.

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The incident occurred at the Lt. Michael P. Murphy Memorial Park on Lake Shore Road just before 7 p.m., police said. Police said children playing in the water picked up what they thought was a rock -- only to find it was a grenade.

The age of the children was not released by police.

Police said the grenade "appeared to have been in the water for some time." It was unclear, however, how long. The incident remained under investigation Monday.