The trio had visited the Chembarambakkam lake along with a few other relatives after lunch.
Police said Afsana and Suhail slipped and fell into the lake from the sixth gate and Usman too jumped to rescue his children.
However, since all three went missing, the other kids raised an alarm and passersby immediately alerted the Fire and Rescue Services and police, apart from trying to rescue the victims.
Before they could trace Usman, he had drowned. His body was retrieved.
On information, Kundrathur police and personnel from Poonamallee Fire Station launched a search for the missing kids. Later, a scuba diving team from Marina reached the spot and retrieved the children’s bodies around 6.30 pm. The bodies were sent to Chromepet GH for postmortem.
Kundrathur police are probing whether it was an accident or Usman purposefully jumped into the lake along with kids to end lives.