Thirteen people have died and 251 have been injured in a toxic gas leak from a storage tank at Jordan’s Aqaba port, state television reported, as authorities called on residents to shut windows and stay indoors.

The leak on Monday came after a cable lifting a tank filled with 25 tonnes of chlorine snapped, sending the container crashing down.

A video posted on state television’s Twitter page showed the tank slamming into the deck of a ship, releasing clouds of yellow gas that sent dock workers racing away.

City health authorities advised residents to close their windows and stay in their homes, according to state TV.

The deputy chief of the Aqaba Region Ports Authority, Haj Hassan, told the local broadcaster Al-Mamlaka that a “cable carrying a container containing a toxic substance broke, resulting in the fall and escape of the poisonous substance”.

The channel cited a former head of the company that operates the port, Mohammed al-Mubaidin, as saying a vessel had been waiting to load almost 20 containers of liquified gas “containing a very high percentage of chlorine”.

He said the gas was heavy and “it is not easy for its gas clouds to move … as it concentrates in one area and is affected by wind movement”.

Chlorine is a widely used disinfectant and water purification agent, but if inhaled, the gas turns to hydrochloric acid, which can lead to internal burning and drowning through a reactionary release of water in the lungs.

Aqaba’s southern beach was reportedly evacuated after the incident.

Local media showed members of the civil defence forces and medics rushing to the scene of the leak wearing masks.

The injured were transported to two state hospitals, one private facility and a field hospital. Aqaba’s health director, Jamal Obeidat, said hospitals were full and the injured people were in “medium to critical condition”.

Health ministry officials said they expected only a handful of people to remain in hospital by Tuesday.

Jordan’s Aqaba grain silos halted work to allow inspection of its grains and for any signs of contamination, but maritime traffic at Aqaba ports continues, officials said.

There were no vessels unloading any grains cargo at the time of the incident, they added.

Aqaba port at the north end of the Red Sea has long been a major transit route for Iraqi imports and exports.

The Jordanian prime minister, Bisher al-Khasawneh, arrived at Aqaba and headed to a hospital where some of the injured were being treated, state TV reported. Al-Khasawneh also formed an investigation team into the incident, chaired by the interior minister, state TV cited the information minister as saying.