A Philippine ferry with 251 people on board capsized during bad weather on Thursday off an island near the capital, Manila, a coastguard spokesman said, and media reported four people had been killed and 140 rescued.
Coastguard boats and army helicopters headed to the vicinity of Polillo island, trying to take advantage of daylight, coastguard spokesman Armand Balilo told media.
Domestic radio reported four dead, and 140 saved, but Balilo said that had not been confirmed.
"We heard about casualties, but we are still trying to get a complete picture," he said.
Accidents involving boats sailing between the many islands of the Philippines are common. Vessels are often overloaded but Balilo said that was not the case on Thursday and the ferry had the capacity to carry 280 people.
Rescue operations were hampered by heavy rain and huge waves caused by a tropical storm affecting the southern Philippines.
Balilo said a distress call had been issued before noon after the ferry capsized about 9 miles off the town of Real, in Quezon province.
"There is a big possibility the accident was caused by the bad weather," he said.
A tropical storm is expected to make landfall on the southern island of Mindanao late Thursday or early on Friday.
The weather bureau has warned of extensive flooding and landslides as the storm, packing center winds of 65 kph (40 mph), approaches the Philippines.