MALINA, April 23 (CGTN) -- Philippine rescuers were scrambling Tuesday to reach dozens of people feared buried under a building near Manila that collapsed a day earlier in a powerful earthquake. The death toll has climbed to 11.

The 6.1 magnitude quake struck northwest of the capital on Monday, scientists from the U.S. Geological Survey said, heavily damaging an airport and sending terrified locals fleeing swaying high-rises.

The worst of the damage was in the province of Pampanga, which was the site of all 11 fatalities, disaster officials said. Dozens of others were injured by falling rubble, including in Manila.

The toll could rise as crews fanned out across the region to assess damage in isolated hamlets that lost power and communications in one of the area's strongest tremors in years.

Scores of rescuers in the town of Porac were wielding cranes and jackhammers to peel back the pancaked concrete structure of a four-story building where up to 30 people were unaccounted for.

"They (rescuers) still hear at least one person who is still alive," Pampanga Governor Lilia Pineda said. "This person is buried under concrete slabs."

The quake also damaged several centuries-old churches which were crowded with worshipers in recent days as the majority-Catholic Philippines marked the Easter holiday.

High-rise buildings in the capital swayed after the tremor struck Monday evening, leaving some with large cracks in their walls.

The quake was centered on the town of Castillejos, about 100 kilometers (62 miles) northwest of Manila, local geologists said.

The Philippines is part of the Pacific "Ring of Fire", an arc of intense seismic activity that stretches from quake-prone Japan through Southeast Asia and across the Pacific basin.