Indonesian Boeing 737 crashes after takeoff with 62 on board

A Shuvijaya Air flight, SJ182, departed from Jakarta's Sokarno Hata International Airport on January 9th, but disappeared from radar shortly after takeoff. The Boeing 730-7500 was delayed and took off at 2:36 PM, vanishing at 2:40 PM. Fishermen reported hearing an explosion and a splash. Flight tracking data showed the plane fell over 3000 meters in less than a minute. There were 50 passengers, including children and babies, and 12 crew members, all Indonesian.

What significant event did fishermen report hearing?

What was the altitude drop of the plane before it disappeared from radar?