DALLAS (CBSDFW.COM) – Lifeguards had to pull two children from a Dallas city pool after they slipped under the water and didn’t immediately return to the surface Tuesday.

Dallas Fire Rescue spokesman Jason Evans said the children, two boys aged six and seven, “went under” the water at about 1:53 p.m. at the Samuel-Grand Swimming pool in the 3200 block of Samuel Blvd.

Fire officials responded to a “near drowning/water injury,” Evans said, and they took one boy to Children’s Medical Center and the other to Baylor Hospital. Lifeguards performed CPR on the two before DFR arrived.

The city’s pools opened on June 2, just three days before the incident.

The children are alive, although authorities have not identified them or announced their conditions.

The two were part of a field trip of 57 students at the pool.  A total of 4 lifeguards and the pool manager were on duty.

The city’s preliminary investigation determined the staff responded appropriately.