Fighting between the rival groups broke out after premier Somchai Wongsawat flew in from a foreign trip to receive the news that the army chief had asked him to call elections in a bid to end months of political protests.
'There was an argument between a red shirt group and a yellow group in front of the radio station and a man was attacked and killed,' Lieutenant Colonel Atipong Thongdaeng of Chiang Mai police told AFP.
He said it was not clear whether the victim was from a pro-government group, which usually wear red clothes, or if he was part of the movement against Mr Somchai's administration, which is often clad in yellow.