DAVAO/SAN JUAN, Philippines: Eleven people including many high school students were killed when a bomb exploded aboard a bus in the southern Philippines on Tuesday, military spokesmen said.

The bus operated by the Rural Transit company was travelling through the town of Maramag in the strife-torn island of Mindanao when the bomb went off, said regional spokesman Major Christian Uy. The blast also injured 21 people, he told AFP.

Many of the victims were high school students who had just boarded the bus as it passed a school in the town, said Lt. Norman Tagros, spokesman for a local infantry brigade.

The bomb went off almost immediately after the students got on.

Tagros said extortion was being eyed as the likely motive. The bombing was the latest in a series of attacks on the bus company.

Last month a bomb exploded aboard a Rural Transit bus in Mindanao, leaving four people injured.

Ten people were killed when a bomb exploded aboard a bus operated by the same company on Mindanao in 2010, which was blamed on an extortion scheme linked to Muslim extremists.

Meanwhile the storm that began as a frighteningly powerful typhoon started to blow away from the Philippines Tuesday after leaving at least 27 people dead and forcing more than 1.6 million into shelters.

The government won praise for unprecedented preparations that were credited for saving lives.

President Benigno Aquino spearheaded what the UN said was one of the biggest peacetime evacuation efforts ever.

Nearly 1.7 million people sheltered in evacuation centres as Hagupit passed their areas, according to government figures, and aid agencies hailed the strategy as a template for coping with future disasters.

The military flew emergency flights with food, water and other essentials from Cebu to the worst-affected areas on Samar on Tuesday.

Interior Minister Manuel Roxas said 200,000 people were believed to be in need of help on eastern Samar, but this could rise as more comprehensive assessments were carried out in isolated communities.

Typhoon Hagupit dissipated into a tropical depression after crossing Lubang Island, 135 km southwest of Manila, and was blowing into the South China Sea, forecasters said.

Batangas, the last major province lashed by Hagupit overnight, has so far not reported any casualties or major damage, echoing similar assessments from many central Philippines provinces spared of major losses.

“With God’s grace, there are zero casualties and no injuries because we were able to prepare,” said Mayor Rodolfo Manalo of Batangas’ idyllic San Juan town, a flood-prone coastal community popular for its beach resorts, where more than 2,800 villagers fled to a public gymnasium and other shelters before the storm slammed ashore.

In southern Basilan province, Philippine Navy vessels including a patrol gunboat rushed to an island where 18 Chinese fishing boats manned by 250 crewmen dropped anchor, said Capt. Giovanni Carlo Bacordo, head of a navy unit in the area. An inter-agency team inspected the boats, found the fishermen’s papers in order and no illegal items. The team accepted the fishermen’s explanation that they sought shelter from the typhoon while en route from Indonesia to China. The boats were due to sail on Tuesday.

Many of the archipelago’s central provinces were still reeling from last year’s monster Typhoon Haiyan, which left more than 7,300 people dead or missing and a massive trail of destruction, fuelling worries about Hagupit as it approached from the Pacific with menacing gusts of 250 kph last week.

Those concerns meant more than a million people readily fled from villages in the path of Hagupit — Filipino for “smash” or “lash — into government emergency shelters.

Hagupit left at least 21 people dead, many of whom drowned in Eastern Samar province, where the typhoon made its first landfall, according to the Philippine Red Cross. The government disaster-response agency has reported only 11 deaths, saying it was still verifying other reported casualties.

Although Hagupit blew in from the Pacific with enormous force, seasonal cold winds blowing down from China deprived it of the warm and humid seas where it draws power. The typhoon, the 18th to batter this disaster-prone country this year, slowly fizzled out.