South Korea's president says the actions of the captain and the crew of the ferry that capsized last week with 476 aboard were "like murder."
Park Geun-hye said Monday their behavior was "incomprehensible and unacceptable."
"The conduct of the captain and some crew members is unfathomable from the viewpoint of common sense, and it was like an act of murder that cannot and should not be tolerated. Right after the accident, the captain did not immediately follow the evacuation orders of the Jindo Vessel Traffic Services Center (VTS). While telling the passengers to stay where they were, they (the captain and some of his crew members) left the passengers and escaped first. This is legally and ethically something that is unimaginable."
The captain, the third mate and one other crew member were arrested Saturday on charges of deserting their passengers as the ferry was sinking.
Prosecutors said Monday four more crew members have been detained on allegations of failing to protect passengers.
Divers have pulled more than 60 bodies from the sunken boat, as authorities widened their inquiry and released transcripts capturing the confusion as the ship capsized and began to sink. More than 200 people are still unaccounted for. Most of the victims were high school students.
Rescuers saved 174 people as the vessel sank.
A memorial service for many of the victims is planned Wednesday in Ansan, South Korea, home to many of the students on board.
Marine traffic control transcripts, released Sunday, showed that the crew was hesitant to order passengers to abandon ship.
The captain, Lee Jun-seok, has said he did not order an immediate evacuation because he feared the passengers would be in danger from the strong currents and the cold water, which is about 10 degrees Celsius. Mr. Lee was one of the first to leave the ferry.
According to the transcript, Jindo Vessel Traffic Services instructed the crew to get passengers off the boat as other boats rushed to save them after the ferry carrying 476 people began to list.
But crew members told traffic controllers that their attempts to order an evacuation were stymied by a faulty announcement system.
Tracking data shows the ship took a sharp turn while navigating a group of small islands off South Korea's southwestern coast.
South Korean prosecutors say the ferry was being steered by a 26-year-old third mate who was navigating the area for the first time.
Authorities have confirmed that the ship's captain was in his quarters, leaving the inexperienced third mate at the helm.
Authorities have not established the cause of the disaster, but some survivors report hearing a loud impact noise before the vessel tilted and began sinking.
On Friday, Yonhap quoted investigators as saying the ferry's sudden turn may have caused 180 vehicles and nearly 1,200 tons of freight to shift, making the vessel to list to one side.