Rescuers are struggling in the largest city near the epicenter of Saturday's magnitude-8.8 megaquake which already claimed the lives of more than 300 people.

Local authorities feared that the death toll would grow as the city has a population of over 200,000.

In Concepcion, an estimated total of over 100 people are still trapped in a toppled 11-story apartment building which was newly-opened. The floors of the apartment building suddenly became vertical as it fell onto the ground.

It took rescuers and firefighters almost 24 hours to pull out 16 people alive and recovered six bodies from the building.

Chilean President Michelle Bachelet already declared a "state of catastrophe" for central Chile.

The downtown area of Concepcion was mostly reduced to rubble and most city residents remained outdoors for fear of aftershocks.

Fire were ablaze in buildings in Concepcion including those of a university.

Gas pipes and power lines were snapped by the strong jolt which was among the world's eight strongest earthquakes ever recorded.

Though the tsunami warning was lifted, many residents still remained on the hills of a city park. The tsunami set off by the initial jolt killed five people and left 11 others missing on the Chilean island of Robinson Cruse.

The highway linking Santiago and Concepcion was re-opened though the road was badly damaged and a one-way traffic took more than 10 hours to complete.

Military personnel were seen reinforcing local police force in patrolling the streets in the city, which is 500 km away from the Chilean capital of Santiago.

On Sunday, a strong aftershock measuring 6.1 on the Richter scale struck off the coast of central Chile near Talca.

In all, 90 aftershocks of magnitude 5 or greater occurred across Chile within 24 hours of the initial megaquake.

Chile is an earthquake prone country. Of the world's recorded 12 strongest quakes measuring over 8.6 on the Richter scale, four occurred in Chile including the world's strongest ever in 1960 when a magnitude 9.5 megaquake killed at least 1,655 people with the temblor and an ensuing tsunami.

(Xinhua News Agency March 1, 2010)