(Adds parents, details of search)
By Ju-min Park and Jungmin Jang
JINDO/MOKPO, South Korea, April 19 (Reuters) - Angry relatives of more than 200 people, mostly children, missing inside a sunken South Korea ferry demanded authorities act now to raise the vessel and hit out at officials, including the country's president, as hopes of finding survivors faded.
Divers saw three bodies floating through a window of a passenger cabin on Saturday but were unable to retrieve them, the coastguard said.
Grieving parents and others gathered in a gymnasium in the port of Jindo, the rescue centre for the operation, were shown murky underwater video footage of the hull of the ship on Saturday for the first time.
It was impossible to see any bodies in the footage viewed by relatives and reporters at the site.
"Please lift the ship, so we can get the bodies out," a woman who identified herself as the mother of a child called Kang Hyuck said, using a microphone in the gymnasium where hundreds of people have spent day and night since the ferry capsized on Wednesday.
"(President) Park Geun-hye should come here again," she said of the South Korean leader who visited the site on Thursday.
Of the 273 missing, most are children from a single high school on the outskirts of the South Korean capital of Seoul. Some parents were giving DNA swabs so rescuers can identify the corpses.
Three cranes have been moved to the site of the rescue operation, but have not yet been deployed and divers have not been able to gain entry to the ship due to fast tides and murky water conditions. The weather was deteriorating in the afternoon, meaning the divers may not be able to start the operation on Saturday.
Divers tried to break the glass to get at the three bodies they saw on Saturday, but failed to do so, the coastguard said.
Coastguard spokesman Kim Jae-in said the cranes would be deployed when the divers said it was safe to do so.
"Lifting the ship does not mean they will remove it completely from the sea. They can lift it two to three metres off the seabed," he said.
The cause of the capsize has not yet been identified, but the investigation has centred on what may have been a sudden turn by the Sewol ferry that may have caused its cargo to shift.
The capsize occurred in calm weather on a well-travelled 400 km (300 mile) sea route from the mainland port of Incheon to the holiday island of Jeju some 25 km (15 miles) from land.
The ship's veteran captain, 69-year old Lee Joon-seok, faces five criminal charges and was arrested on Saturday along with two other crew members, according to coastguard officials.
Lee was not at the helm or on the bridge when the ferry capsized, although crew members said he tried to right the ship later. Witnesses say that he and other crew members escaped from the stricken vessel before giving orders for the passengers to escape.
The third mate, who had the helm at the time of the capsize, was one of those arrested.
The 20-year old ferry appeared to have a clean bill of health, based on its inspection record, although police have seized records from the ship owners, Chonghaejin Marine Co Ltd, and of the company that supervised the loading of the vessel.
Yonhap news agency said there were 180 vehicles being carried by the ferry along with 1,157 tons of freight. At least some of the freight was in containers stacked on the foredeck of the ferry.
Relatives and friends of the schoolchildren have also gathered at the Danwon High School in the commuter town of Ansan. The vice-principal of the school, Kang Min-gyu, 52, was one of those rescued.
He hanged himself outside the gym in Jindo, police said.
Kang was discovered on Friday and police released part of a two-page suicide note.
"Burn my body and scatter my ashes at the site of the sunken ferry. Perhaps I can become a teacher for the missing students in my next life," he wrote. (Additional reporting by Chookyung Kim; Writing by James Pearson and David Chance; Editing by Nick Macfie)