Six persons were killed and many feared drowned in the Yamuna river as a boat capsized on Thursday in Uttar Pradesh's Baghpat, police said.The overcrowded boat was headed for Haryana when the incident occurred.Police and Provincial Armed Constabulary divers reached the accident spot and have begun rescue operations, an official told IANS. So far, six bodies have been fished out. There is no trace of over a dozen others who were in the boat. The police fear number of casualties might rise.A few people have been rescued and admitted to a nearby medical facility.Villagers told the police the boat was overcrowded, which could be one reason for the tragedy.