MANILA, Philippines?Alejandro "Bong" Reblando, a veteran Filipino journalist and former Associated Press stringer, was among at least 18 reporters killed in an attack on an election caravan, authorities said. He was 53.

The attack Monday left 57 dead in the Philippines' worst election massacre.

Reblando and the other journalists were accompanying relatives and supporters of a gubernatorial candidate in Maguindanao province when they were ambushed and shot dead.

Media groups say it was the highest number of reporters killed in a single attack anywhere in the world.

Based in General Santos City, Reblando covered the southern Philippines for The Associated Press from the late 1980s to the early 2000s. He was recently named a regular staffer for Manila Bulletin daily.

His coverage of the region included the Muslim separatist insurgency as well as local politics.

Aquilles Zonio, General Santos reporter for the Philippine Daily Inquirer, said Reblando was considered a "big brother" by his younger colleagues.

Reblano is survived by his wife and seven children.