KEEGO HARBOR, Mich. -

The 911 calls from a tragic boating accident in July on Sylvan Lake offer new insight about the rescue effort.

Two children -- 11-year-old Alexander Mansour and his 6-year-old sister Gabrielle -- died after the tube they were being pulled on was hit by a boat.

Several bystanders called 911 within moments of the crash.

Read back: Sylvan Lake community in shock after deadly accident

911 caller: They're like 20 feet off the beach. People are trying to help them. This speed boat just ran over these kids on a tube.

Another 911 caller: My emergency? I just saw a boat hit a tube. Just ran over a tube that has kids on it.

Time seemed to tick by very slowly as emergency crews rushed to the lake. Urgency can be heard in the voice of one 911 caller who knew the victims did not have much time.

After the accident, the Oakland County Sheriff's Department decided to bring back marine patrols on Sylvan Lake which previously had been stopped due to budget constraints.