Two helicopters collided midair near an airport on May 17, leaving no survivors
There were a total of five people on board the helicopters, which were registered outside of Finland and traveling from Estonia
The investigation into the collision is ongoing, and it could take up to a year, authorities said
Multiple people are dead after two helicopters collided and crashed near an airport, leaving no survivors.

A total of five people died in the incident — which took place in Kauttua, Eura, near the Eura Airport in southwestern Finland — on Saturday, May 17, according to an official news release from Finland’s National Bureau of Investigation (NBI).

According to flight plans, there were two people on board one of the helicopters and three in the other, Finnish police said. Both aircraft were destroyed in the collision and subsequent crash.

An emergency call reported the collision to police at around 12:35 p.m. local time, and first responders arrived “quickly” at the scene of the accident, according to the NBI. All five passengers were pronounced dead at the scene, authorities later revealed in a press conference held on Sunday, May 18, per Estonian Public Broadcasting.

The NBI did not immediately respond to PEOPLE’s request for comment on Sunday, May 18.

The crash site, a wooded area, has since been isolated, police said, adding that the helicopters were located a little over 300 feet apart from each other.

Both helicopters involved in the crash were civil and registered outside of Finland, police said. They were traveling from Tallinn, Estonia, to Piikajärvi in Kokemäki, according to the NBI. (The Piikajärvi Airport is located about 9.3 miles from the Eura Airport.)

Finnish and Estonian authorities are now “working closely together in response to the accident,“ Johannes Siirilä, detective chief inspector of the NBI, said in an official statement.

The NBI is also cooperating with the Southwestern Finland Police Department on the investigation, the bureau said. Police are currently investigating the details of the helicopters and the crash itself.

The Safety Investigation Authority is also conducting its own investigation at the crash site, per the NBI.

The NBI’s Robin Lardot said that the investigation is currently focused on the distance maintained between the two aircraft, as well as their altitude at the moment of the fatal May 17 collision, Estonian Public Broadcasting reported.

What is left of the two helicopters — which were revealed to be Robinson R-44 models — have been sent to the city of Turku for investigation, according to the Estonia outlet.

Autopsies of the five victims will also take place in the Finnish city.

Though Finnish authorities declined to comment on the identities of the deceased, Estonian Public Broadcasting identified three of the crash victims as businessmen Oleg Sõnajalg and couple Priit and Lilit Jaagant.

As for the cause of the crash, Tiina Bieber with the Finnish Safety Investigation Authority said investigators cannot say whether it was human error or malfunction, per Estonian Public Broadcasting.

Bieber also said that the investigation could take nine months to a year.