HRABOVE, Ukraine — With the sound of artillery blasts at a distance, 70 international investigators arrived Friday at the eastern Ukraine site where Malaysia Airlines Flight 17 crashed and started recovering the remains of as many as 80 victims that have been lying in farm fields for two weeks.

Several hours before they arrived, at least 10 Ukrainian soldiers were killed when their convoy was ambushed by pro-Russian separatist rebels in a town close to the wreckage site. Thirteen more soldiers were unaccounted for after the attack, officials said, and the bodies of four more people were being examined to determine whether they were soldiers or rebels.

But the team was able to launch what is expected to be a painstaking search and “brought back all the human remains they found,” said Ilona de Ruyter, a spokeswoman for the Dutch-led recovery operation. She provided no further details on the remains.

The investigators from the Netherlands and Australia, plus officials with the Organization for Security and Cooperation in Europe, traveled from the rebel-held city of Donetsk in 15 cars and a bus to the crash site outside the village of Hrabove.

As they set up a base to work from at a chicken farm, an Associated Press reporter heard artillery fire in the distance. It was impossible to tell how far away shells were landing and whether the Ukrainian army or rebel forces were firing.

The investigative team’s top priority is to recover human remains that have been rotting in midsummer heat of 90 degrees since the plane went down July 17. They will also try to retrieve the belongings of the 298 people killed aboard the Boeing 777.

After they arrived, members of the team wearing gloves broke up into small groups and walked into fields of scrub.

Team members gathered around plane wreckage, taking photographs of debris from the jet’s fuselage and tail. Rebel fighters guarding the perimeter of the zone stayed away from the investigators and some patrolled the streets of the neighboring village of Rozspyne.

Ukraine and the West contend the plane was shot down by the rebels with a Russian-supplied missile. Rebel leaders publicly deny it, but one top rebel official told the AP on condition of anonymity that insurgents were involved in the operation that downed the plane.

Friday’s search effort came after a smaller advance investigative team managed to perform a preliminary survey of the area a day earlier. For days, clashes along routes to the wreckage site had kept investigators from reaching the site. Independent observers warned there has been tampering with evidence.

The sprawling site of fields in between two villages is now designated a crime scene and was being divided into grids for systematic searches for remains, belongings and jet crash evidence, Australian police officer Brian McDonald told reporters in Hrabove. Specially trained dogs will be also be used in the search, McDonald said.