Ms Park said that those to blame would have to take “criminal and civil” responsibility for their actions.
She spoke out as divers continued to recover bodies from the ill-fated ferry Sewol, which sank last Wednesday, as they gained access to more of the submerged hull.
Sixty-four people are known to have died and 238 are missing, presumed dead. Most of the victims are high school pupils aged 16 and 17.
Captain Lee Joon-seok, 69, and two other crew members were arrested last week on negligence charges, with prosecutors yesterday announcing four further arrests – two first mates, one second mate and a chief engineer.
Mr Lee was also charged with undertaking an “excessive change of course without slowing down” while traversing a narrow channel.
Several crew members, including the captain, left the ferry as it was sinking, ahead of passengers, witnesses have said.
Ms Park said the crew’s desertion was tantamount to murder.
“Above all, 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,” she said.
Mr Lee said in a promotional video four years ago that the journey from the port city of Incheon to the holiday island of Jeju was safe – as long as passengers followed the instructions of the crew.
He also told the Jeju Today newspaper that he had been involved in a sea accident off Japan years before. The irony of his commments in the video is that, during last week’s disaster, crew ordered passengers to stay in their cabins as the ferry sank.
Many of those who escaped either did not hear or flouted the instructions.
Of the 476 passengers and crew on board, 339 were children and teachers on a high school outing.
In the 2010 promotional video, Mr Lee said: “Passengers who take our ship to and from Incheon and Jeju can enjoy a safe and pleasant trip and I believe it is safer than any other vehicle as long as they follow the instructions of our crew members.”
As he was taken from a court in Mokpo on Saturday, Mr Lee explained his decision to wait before ordering an evacuation.
“At the time, the current was very strong, the temperature of the ocean water was cold,” he told reporters.
He said he feared that passengers, even if they were wearing life jackets, could drift away from the ship “and face many other difficulties”.
He added that rescue boats had not yet arrived, and that there had been no civilian vessels nearby.
Meanwhile, parents of the children missing in the accident – in what is likely to turn out to be one of South Korea’s worst maritime disasters – sat exhausted from days of grief yesterday, waiting for the almost inevitable news that their loved ones had died.
They have spent all their time since the accident in a gymnasium in the port city of Jindo, taking it in turns to vent their anger at the crew’s inaction and slow pace of the rescue operation.
One of those waiting in the gymnasium was Kim Chang-gu, whose son Kim Dong-hyup is among the missing.
“I dream about him and hear hallucinatory sounds,” he said.
“Somebody told me he was alive but I now have given up. I know how he said ‘Dad’. I keep hearing that.”