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LEBANON, Ind.––Officials said fire crews responded to the Witham Family YMCA on N. Lebanon Street around 10:40 a.m. Wednesday on a reported incident involving hazardous materials.

When Lebanon fire units arrived on scene, they found “a large chemical vapor cloud outside the building.”

Officials said several children were on site attending day camp at the time, and were evacuated with the help of units from Lebanon and Center Township Fire Departments along with Lebanon Police Officers, and Boone County EMS personnel.

Employees of the facility were also evacuated from the YMCA premises. Witham Hospital and Crown Pointe Senior Living Community were told to shelter in place at the time.

The children were taken to a safe area to wait for parents and guardians to arrive. After everyone was accounted for, firefighters entered the building.

Lebanon authorities said firefighters located, contained, and diluted the chemicals involved.

A Hamilton County HazMat response team was requested by the Lebanon Fire Department and was on the scene investigating as of 2:00 p.m. Friday.

Fire officials and investigators said they believe the cause of the vapor cloud was an accidental mixture of pool chemicals.

According to investigators, a pool maintenance contractor “mistakenly filled a chemical holding tank with the wrong compound, causing a chemical reaction.”

The contractor and three other employees were checked out and released by EMS, and no other illnesses or injuries have been reported.