A four-year-old girl drowned at a family celebration on a lake in Brandenburg.

The criminal police are investigating.

A police spokesman said on Wednesday that it had to be clarified how the accident on Tuesday evening at Klempowsee, 70 kilometers north-west of Berlin, could have happened.

"We are assuming a tragic accident." However, as always in such cases, it must be checked "what exactly happened and how it happened".

The child's body should be autopsied.

It is also about the question of whether security obligations have been violated, said the spokesman.

The possibility of neglecting the duty of supervision could also play a role.

On the evening of the accident, the police had questioned the first witnesses and also deeply affected family members.

The interrogations were to continue on Wednesday.

The family celebrated on Tuesday evening near the southern tip of the long lake near Wusterhausen (Ostprignitz-Ruppin district).

There is a campsite and a restaurant there.

The little girl was missing around 6:30 p.m., a police spokesman reported.

At 6.40 p.m. the alarm call was received by the police.

A large-scale search operation by police officers and the fire brigade immediately began.

The emergency services were supported by many volunteers, as the spokesman said.

A helicopter flew over the area, the forest and banks were searched with sniffer dogs, and firefighters were out on the water in boats.

The child's body was found after about two hours.

She was floating in the water near the shore.

An emergency doctor could only determine the death of the girl.