PUEBLO, Colo. (AP) — No lifeguard was watching over the swimming pool at a southern Colorado mobile home park when two sisters and their teenage baby sitter drowned in the water that is normally crowded in the summer, authorities and neighbors said Tuesday.

Police were canvassing the neighborhood in the city of Pueblo to interview people who may have seen the three girls drown Monday afternoon. Foul play was not suspected in the deaths of 3-year-old Azucena Gandarilla; her sister, 6-year-old Amaya Gandarilla; and their 17-year-old baby sitter, Joo Lee.

A 911 caller reported the drownings, and emergency responders could not revive the girls.

Police said the sisters lived in the Pueblo Grande Village mobile home park about 105 miles south of Denver, but they were not sure where the teen lived.

Neighbor Ruth Wright said she didn’t know the girls by name but that children packed the pool during the summertime. Wright says neighbors are shocked by the drownings.

The pool reached a depth of about 8 feet.