Toronto police have arrested a man in his 30s after at least three people -- including a baby and a toddler -- fell from a fourth-floor balcony in the city's east end.

The incident happened shortly after 4 p.m. on Saturday at a high-rise on Scarborough Golf Club Road near Lawrence Avenue East.

An 11-month-old and a 2-year-old were rushed to Sick Kids Hospital. Both are suffering from life-threatening injuries, said Staff Sgt. Barbara McLean.

Police arrested a man in his 30s at the scene. He was treated for minor injuries and has been released from hospital.

A woman in her 30s was also taken to Sunnybrook Hospital.

One witness said he was doing laundry in the building when he heard screaming, and stepped outside to see a baby, "another little child" and a woman lying on the ground.

"It was heartbreaking," Mike Holland said.

Other residents in the building said they heard an argument taking place in the apartment prior to the incident. One of the apartment's windows along the balcony is also shattered.

Police are investigating. No charges have been laid.