A packed tourist ferry has sunk off the Thai resort of Pattaya, killing at least six passengers including three foreigners.
A police spokesman said another 19 people were seriously injured after an alleged mechanical failure near Koh Larn, a small island popular with day trippers.
Dozens of ambulances were called to Pattaya beach to treat casualties pulled from the water.
Television footage showed stunned tourists being led to safety, as people waited anxiously on the shoreline for news about friends and family.
Between 150 and 200 people, many of them Russians, are believed to have been on board the double-decker ferry.
Local media said passengers rushed to one side of the boat following an engine failure, causing it to list.
"The boat went down in minutes. I saw people -- some with life jackets, some without -- in the water," said a local dive guide, who was one if the first on the scene.
"One man was holding on to a gas cylinder. There was a body face down in the water. They were all panicking, shouting for help,
"We pulled 60 people from the water, including a Russian boy. We gave him CPR (cardiopulmonary resuscitation) but he was in a very bad way."
Pattaya police chief Colonel Suwarn Chiewnawintawat said three Thai residents, one Chinese and two other foreigners were among the dead.
It is thought everyone else on the ferry was rescued.
"We don't expect to find any more dead. One Russian boy is seriously ill in intensive care," said Col Pattaya.
He added: "The captain ran away. We will issue an arrest warrant for him. Divers will recover the boat today. We still don't know the cause."
Some 22 million tourists visited Thailand last year.
Pattaya, around 100 miles (160 kilometres) southeast of the capital Bangkok, is one of the country's most popular resorts.
It is renowned for its vibrant nightlife and cheap accommodation and is a favourite destination among Russians..