Eight workers have been killed in a chemical accident at a major bank in the Thai capital.
A chemical agent was mistakenly released during an upgrade of the fire extinguisher system at the Siam Commercial Bank (SCB) in Bangkok on Sunday night, officials said.
Seven people were also injured when the suffocating cloud of chemicals was released at the bank's head office.
SCB said in a statement that contractors appeared to be to blame for setting off the system.
Seven people were injured in the accident
"From the preliminary investigation by the police, the incident may have been caused by the negligence of contractors who were hired to make additional improvements to the building's fire security system," it said.
The employees turned on a system that released pyrogen aerosol, which is normally intended to deprive fire of oxygen, the bank said.
"As a result, there was loss of life and injuries ... the injured are now being treated in hospitals," it said.
Pyrogen makes a type of aerosol fire extinguisher which is used in places where putting out a fire with water would damage documents or electrical equipment.
A system that released pyrogen aerosol was turned on, the bank said
Police said those killed were seven contractors and a security guard.
"They were in the building for maintenance work," said Police Colonel Charoen Srisasalak.
SCB, Thailand's oldest commercial bank, expressed "deep regret" for those affected by "this unfortunate incident".
"The bank will provide initial assistance as deemed appropriate," it said.
It said the rest of the building was not affected and remained open for business.