Fort Worth, Texas ? With their hotel pool closed for cleaning and the Texas heat reaching nearly 90 degrees, Myron Dukes took his two children and another child to check out the fountains and pools at the park across the street.

Within minutes, all four drowned in a swirling, decorative pool posted with no-swimming signs. Authorities said powerful suction apparently pulled the victims to the bottom of the 9-foot pool at the Fort Worth Water Gardens.

Witness accounts of the accident varied, but 8-year-old Lauren Dukes apparently slipped and tumbled into the water. Her 11-year-old friend, Juantrice Deadmon, tried to reach in and help her but fell in herself. Then 13-year-old Christopher Dukes jumped in to help his sister and the other girl.

Investigators are still trying to determine where 39-year-old Dukes was when the youngsters entered the water, but at some point he jumped in as well.

The victims were among 120 members of a Baptist Church in Chicago attending a national Sunday school convention. About 2,000 of the convention attendees gathered Thursday morning for a prayer vigil.

“Today our city extends our wings to enfold and comfort you,” Fort Worth Mayor Mike Moncrief told the crowd, many of whom held hands and wiped away tears. “We are very, very sorry about your loss.”

Though the Water Gardens are not meant for swimming, residents say people often wade in the pools on hot days.

In the pool where the four drowned, water comes down several irregularly spaced steps, creating waterfalls that empty into the pool. The water there is recirculated through a drain at the bottom of the pool.

Officials did not know whether the suction was created by the drain or the water coming down. Police Officer Tony Moldanado, one of the first rescuers at the scene, told the Fort Worth Star-Telegram that when he jumped in, the suction “literally sucked the socks off my feet.”

Members of the Antioch Missionary Baptist Church, dressed in white, pray during a vigil in Fort Worth, Texas. About 2,000 people gathered Thursday for the prayer vigil near a downtown park where a man and three children from the Antioch Missionary Baptist Church in Chicago drowned while attending a Sunday school conference.