Yesterday's bomb blast was at room named after Thai deputy prime minister

In the 11am local time incident, 21 people with most of them retired military officers were injured when a pipe bomb which was packed with nails and hidden in a flower vase, exploded.

Other rooms located in the vicinity of Wongsuwan Room, a dispensary waiting room, were also named after other high-ranking military officers such as former prime minister and current Privy Council president Gen Prem Tinsulanonda and another former prime minister, Gen Chavalit Yongchaiyudh.

Although the hospital which is located in Bangkok''s Ratchathewi district, near the Victory Monument, is administered and run by the military, it also opens its doors to the public seeking medical treatment.

Yesterday''s bomb explosion happened on the third anniversary of the 2014 military coup which deposed Thailand''s civilian administration, while police investigating the incident have not stated the motive for the incident.

Thai authorities today continue their investigation into yesterday''s blast, which was the most serious incident compared to two other Bangkok''s pipe-bomb explosions in April and last week, which slightly injured four people in total.

Bangkok police chief, Lt Gen Sanit Mahatavorn who visited the hospital and the scene of the blast today, said the police had been doing their best in the investigation and would not rush into arresting anyone without sufficient evidence.

"Police want to make sure the real culprits are prosecuted," he told reporters.

Meanwhile, security has been tightened at Pramongkutklao Hospital with soldiers stationed at the entrance and exit of the hospital.

According to Deputy Defence Minister Gen Udomdej Sitabutr, the National Council for Peace and Order (NCPO) has held a meeting with the army and police following the bombing incident and agreed to tighten security at the hospital and other crowded areas.

National Human Rights Commissioner Angkhana Neelapaijit, in a statement, also denounced the attack on Pramongkutklao Hospital, saying it was an inhumane act as no hospital should be targeted.