The Netherlands prime minister has temporarily suspended search efforts at the site where Malaysia Airlines Flight 17 went down as fighting between pro-Russian rebels and Ukraine forces picked up speed. Some 228 coffins carrying the remains of an unknown number of passengers have been returned to the Netherlands, but investigators continue to recover body parts and debris from where the Boeing 777 fell. Their efforts have been slowed by dangerous conditions in the area.  

"Over the past few days, the security situation in eastern Ukraine — including the MH17 crash site — has been getting progressively worse," Dutch Prime Minister Mark Rutte told reporters in The Hague, the government capital of the Netherlands, on Wednesday.

Investigators trying to reach whatever remains of the missing bodies from MH17 have frequently reported hearing gunfire and shelling in the area. The crash site is a 14-square-mile stretch of meadows and crop fields peppered with villages whose roads are frequently interrupted by rebel and government checkpoints. Skirmishes between pro-Russian and Ukraine forces often occur just a few miles from where investigators are searching, according to The Telegraph.

Following the prime minister’s announcement, Australian officials clarified that inspections would resume once it becomes safe to send investigators back in. “None of us ever experienced anything like this before and we hope never to again,” Cornelis Kuijs, who leads the international recovery team in eastern Ukraine, told the Telegraph. “Besides the tragedy of the crash itself you also have this tension of a war going on around you, which makes it unique.”

About 70 investigators from Malaysia, the Netherlands and Australia and two cadaver dogs arrived at the crash site near the city of Donetsk on Saturday to comb through the wreckage of MH17 for any remains. Pro-Russia separatists and Ukrainian forces agreed to a cease-fire around where the plane’s debris lay, which allowed investigators two days of uninterrupted access to the area. But shelling near the crash site became more frequent this week, prompting the Dutch prime minister to pull investigators out.

A national memorial service for victims of the crash was held Thursday in Melbourne. Australian Prime Minister Toney Abbott attended alongside grieving families and other dignitaries. “We will give thanks for their lives and we will pray for their loved ones,” Abbott said, The Guardian reports. “We will pause.”

Flight MH17 was en route from Amsterdam to Kuala Lumpur when it was shot down on July 17 over Ukraine, killing all 283 passengers and 15 crew members. Of the passengers, 196 were Dutch citizens. Officials hope to confirm the number of recovered bodies sometime within the next few weeks. Dutch forensic teams are working to identify the remains that have already arrived in the Netherlands.