TAIPEI, July 20 (Xinhua) -- A group of four mainland officials arrived in Taiwan on Wednesday afternoon to assist families of victims of a serious tour bus accident.

They are from various departments including the Association for Tourism Exchange Across the Taiwan Straits. Liu Kezhi,secretary-general of the association, told press at Taoyuan Airport that the mainland group would immediately begin discussions with Taiwan authorities, including the Taiwan Strait Tourism Association, on the handling of the accident.

"My heart is very heavy at the moment," he said, adding the other task of the group was to mourn those compatriots who died in the accident and send condolences to their family members.

Twenty-six people, including 23 tourists and a tour guide from the Chinese mainland and two local people -- a driver and a tour guide -- were killed when a tour bus crashed into a highway barrier and caught fire near Taoyuan Airport in Taiwan on Tuesday.

Taiwan authorities are investigating the cause of the accident.