
The airport has been the site of protests since Wednesday, after hundreds of People's Alliance for Democracy (PAD) protesters barged in and camped out here to overthrow what they described as Thaksin Shinawatra's puppet government.
The protest forced airport authorities to cancel all flights.
According to witnesses, an assailant fired a grenade into the inbound passenger terminal building of the Don Mueang Airport from the Don Muang Tollway before dawn yesterday.
"I saw a beam coming and it hit the terminal's glass wall," a witness said.
The explosion caused panic inside the terminal where protesters were sleeping. They woke up and fled to safety, as dozens of bodies were covered in blood.
Ronnachai Chaisri, 29, from Songkhla's Saba Yoi district, died on his way to a hospital. Two injured protesters were rushed to the Central General Hospital, eight others to Bhumibol Hospital and 13 to Mongkut Watana Hospital.
Currently, seven victims remain hospitalised.
"One of them is still in critical condition. She has not been declared out of danger," Public Health Ministry permanent secretary Prat Boonyawongvirot said yesterday.
The critically-injured victim was identified as 66-year-old Phanchawee Supatpong.
Don Mueang Police Station superintendent Colonel Narongrit Promsawat said the grenade attack took place despite the tight watch by policemen and PAD guards.
"There were 80 policemen on patrol last night," Narongrit said.
PAD leaders announced last night that their protest would end at all sites by this morning.
The announcement was made after the Constitutional Court dissolved the People Power Party yesterday.