Supt Kevin Purcell, of West Mercia Police has said four children were playing near the lock, but two fell in and another then went to try and get them out, while the fourth ran home to raise the alarm.
This video shows the canal where three children entered the water. Police say they are 'working hard to establish exactly how Imie came to be in the water'.
Supt Purcell said West Mercia Police would be working with the council to support children from Imie Harrison's school in Kidderminster, after the six-year-old died following a fall into a canal on Tuesday.
Police say it was the twin brother of Imie Harrison, the six-year-old girl who died after falling into a canal, who raised the alarm.
Imie and two other six-year-old children were playing near Wolverley Court Lock on the Staffordshire and Worcestershire Canal in Kidderminster when they fell in.
Two children, a boy and a girl, managed to get themselves out of the water and are expected to make a full recovery.
West Mercia Police say the children were playing by the lock when they fell in.
Supt Kevin Purcell, of West Mercia Police said:
This appears to be an extremely tragic accident at this stage and our thoughts are with Imie’s family, who are absolutely devastated by her death. I would ask that their privacy is respected at this time.
“Our investigation into this incident is continuing today and we are working hard to establish exactly how Imie came to be in the water.