A powerful earthquake that killed dozens of people in central Philippines terrorized survivors Tuesday unleashing hundreds of aftershocks, officials said. The 6.7-magnitude offshore earthquake, which struck just before noon Monday, hammered the provinces of Negros and Cebu on the central Philippines\' Visayas islands, triggering landslides, burying homes, destroying roads and bridges, and knocking out essential services. Local seismologists measured the quake at 6.9-magnitude, which also prompted a temporary tsunami alert. The Philippine Star, quoting local officials and Guihulngan City Mayor Ernesto Reyes, said the 29 people earlier reported missing in a quake-triggered landslide in the Negros province are now presumed dead, raising the death toll to 52. Authorities said they were trying to determine the number of people injured. The official death toll reported by the National Disaster Risk Reduction and Management Council, however, stood at 43, most of them killed by collapsed walls and fences. The Star quoted Negros Gov. Roel Degamo as saying the earthquake damaged eight bridges, three of them now unusable. He said soldiers and police were assisting in the rescue and relief operations hampered by inadequate facilities. Schools and government offices remained closed. Earlier, Degamo told ABS-CBN the entire province was without electricity and schools suspended classes. He said the cities of Guihulngan, Tayasan and La Libertad were isolated. GMA News, quoting national seismologists, reported more than 700 aftershocks had been recorded as of Tuesday morning. More of them were expected in the coming weeks. The Philippine Institute of Volcanology and Seismology\'s Winchell Sevilla said the most powerful of the aftershocks measured 6.2-magnitude. The U.S. Geological Survey said the 6.7-magnitude quake struck at 11:49 a.m. local time Monday at a depth of 12.4 miles off Negros-Cebu region, 353 miles south-southeast of the capital of Manila. The epicenter was reported in the sea between Negros Island and Cebu. The Philippines is situated in the Pacific Ring of Fire with frequent earthquakes and volcanic activities.