Horror at new Texas water park on its opening day as 16 people are gassed by dangerous mix of pool chemicals

The grand opening of America's newest water park was thrown into chaos when a chemical spill put 16 people in hospital.

Deadly chlorine gas swept across a pool at Great Wolf Lodge Water Park outside Houston when a construction worker poured bleach into a tank  of sulfuric acid as the celebrations got underway.

Webster Fire officials declared a Hazmat incident and 16 affected workers were rushed to two nearby hospitals in a convoy of ambulances.

ABC's Good Morning America had reported on the opening of the $200 million resort hours earlier, and viewers awoke to the sight of reporter Lori Bergamotto trying out the facilities alongside her husband and children.

'Speeding down slides, floating the Lazy River or jumping the waves, this fun-filled destination is overflowing with adventure for all,' she gushed.

Good Morning America was on sight to report on the opening of the $200 million water park with reporter Lori Bergamotto, right, telling viewers it is 'overflowing with adventure'

Hours later sixteen construction workers were in hospital after a chemical leak on site

Construction work is still taking place on the 27-acre site which was originally due to open over the Labor Day weekend.

Webster Fire Chief Dean Spencer said an investigation was underway after first responders were alerted to reports of breathing problems in the pool house that operates an outside pool.

A building was evacuated and the injured men were hosed down before being taken to hospital.

'A third-party contractor at Great Wolf Lodge improperly mixed pool chemicals, causing a chemical reaction,' the City of Webster said in a statement. 'This occurred in an isolated building separate from the hotel and waterpark.

'Approximately five individuals evacuated the building. Sixteen employees and contractors working in the immediate area were transported to HCA Clear Lake Hospital and UTMB Hospital, with decontamination completed beforehand.'

The water park is the Chicago-based company's 22nd resort in North America, and its second in Texas.

Singer Kelly Rowland was at the opening to see attractions including the 'Otter Cave Waterworks' featuring spray jets, body slides, and a 1,000-gallon tipping bucket.

A 95,000 square-foot indoor water park sits alongside the 58,000 square-foot Great Wolf Adventure Park complete with a 532-room hotel.

The company is expecting to receive 500,000 visitors a year, while construction work on the three-year project has created 650 jobs.

Spencer said the injured staff worked for the contractor Hawkins, and that some had been transferred to hospital as a precaution.

Singer Kelly Rowland was among the VIPs at Wednesday's opening ceremony

The $200 million attraction was originally supposed to open in time for the Labor Day weekend

The injured men were decontaminated before being taken to hospital in a fleet of ambulances

'The situation was quickly contained and will not affect the Lodge's operations,' he added.

'At this time, there is no issue with the chemicals. They have all been resolved.

'An environmental company is working with Great Wolf Lodge and the contractor to clean the tanks safely.'

The park's chief brand officer Brook Patterson told Bergamotto that that Great Wolf Lodge is the 'ultimate stress-free family get away'.

A spokesperson for the resort said the safety of its guests and 'pack members' is always its priority.

'We greatly appreciate the quick actions of first responders from the city of Webster in response to an incident at an external building outside of the main indoor water park and resort caused by an external vendor,' they added.

'We've received the all-clear to open the resort and all water park attractions as planned from the Webster Fire Department.'