Patients were evacuated from a hospital in the capital after anti-government protesters forced their way into the grounds to look for soldiers they believed were hiding there.
The so-called "red shirts" from the the People's Alliance for Democracy (PAD), later apologised for the incident.
Patients at Bangkok's Chulalongkorn Hospital were sent to other hospitals and all non-emergency services were suspended after the brief incursion by about 100 red shirts on Thursday night.
Dr Weng Tojirakarn, a PAD leader, issued a "deep apology" for the raid, calling it "inappropriate, too much and unreasonable".
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