A patient who stabbed a psychiatrist with a fruit knife at King Chulalongkorn Memorial Hospital is being held in custody pending a full psychiatric evaluation.
Pol Maj Gen Piya Tawichai, Metropolitan Police deputy commissioner, said the man would be sent to Somdet Chaopraya Institute of Psychiatry.
A letter from the institute was needed to confirm whether he suffered from mental illness before a decision on legal proceedings was taken, Pol Maj Gen Piya said.
The attack occurred on Tuesday and details were widely shared on social media.
The victim was Athicha Wattana-udomchai, a psychiatrist at the hospital.
She was stabbed in the chest and seriously injured.
A call went out for donations of B Rh+ blood.
Dr Suthipong Vacharasin, director of King Chulalongkorn Memorial Hospital, said the attacker was a patient at the hospital.
"The doctor is now safe, so the blood donations are not needed. I would like to offer my thanks to all well-wishers," he said.