(BBC) – The South Korean authorities have arrested four more crew members from the ferry that sank last week, bringing the total number detained to 11.

Police have also raided offices of companies linked to the ferry’s owners. Search teams are continuing to recover bodies from the submerged hull of the passenger ferry. One survivor has described taking the agonising decision to save himself as the ship capsized and water washed away students he was trying to rescue. The number of people known to have died in the accident has reached 150, with another 152 still missing, most of them teenage children from a single school in Ansan, outside the capital Seoul. An emotional memorial service took place near the school on Wednesday, with friends and family members laying flowers in front of photographs of some of those who died.

The government is under strong public pressure to find out why the ferry capsized. Twenty-two of the 29 members of the ferry’s crew survived and prosecutors say the 11 arrested were on the bridge when the ship listed and sank within two hours of distress signals being sent. The BBC’s Jonathan Head on the island of Jindo, where the recovery operation is being co-ordinated, says authorities are moving quickly against those they blame for the disaster. Companies associated with Incheon-based Chonghaejin Marine Company, which owned the 6,825-tonne Sewol ferry, have also been raided by police as part of the investigation.

Authorities have issued 30-day travel bans to more than 70 executives connected with Chonghaejin and its affiliates while they are investigated on possible charges ranging from criminal negligence to embezzlement.

“We will also make efforts to retrieve profits made out of criminal acts and track down hidden assets to support financial compensations for [potential] lawsuits by families of the victims and the missing,” a prosecutor told AFP.

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