Four people who died when a small plane crashed at London Southend Airport are believed to be foreign nationals, police have confirmed.

The airport has been closed since emergency services were called to the incident involving a Beech B200 Super King shortly before 16:00 BST on Sunday.

Witnesses described a “fireball” type explosion soon after the Netherlands-bound light aircraft had taken off.

All four people were killed in the crash – two pilots and two passengers – and Essex Police said in a press conference on Monday it believed they were foreign nationals.

The names of the four who died have not been released but officers are now working to confirm their identities.

Ch Supt Morgan Cronin said the victims would be “treated with the utmost respect and dignity”.

The Civil Aviation Authority (CAA) has put in place a significant air exclusion zone surrounding the crash site.

All flights to and from the airport on Monday have been rerouted, with passengers advised to check with their airline for advice.

The Beech B200 Super King Air plane was operated by Zeusch Aviation, based at Lelystad Airport in the Netherlands, which has confirmed it is “actively supporting the authorities with the investigation”.

The plane had flown from the Greek capital Athens to Pula in Croatia on Sunday before heading to Southend. It was due to return to Lelystad on Sunday evening.

Detectives and forensic teams are working in parallel with the Air Accidents Investigation Branch (AAIB), the Royal Air Force, Essex County Fire and Rescue Service and London Southend Airport to work out what happened.

Speaking at the press conference, Lisa Fitzsimons, a senior inspector at the AAIB, said it was “too early to speculate on what caused this tragic accident”.

“If there are safety lessons that can be learned, we will make recommendations that will aim to prevent a similar accident occurring,” she said.

Eight of its inspectors are now at the crash site.

A London Southend Airport spokesperson said: “Our thoughts are with those affected by [Sunday’s] events and all passengers impacted by this disruption.

“We will restart flight operations as soon as possible and will continue to update the public on developments.”