The already grim situation at the crash site of Malaysian Airlines Flight MH17 in Ukraine has only grown more dire nearly two weeks after the tragedy, with international investigators reporting Tuesday that they were unable to get to the area because of safety concerns for the third day in a row.

Australian Federal Police responsible for protecting the forensic investigators from Malaysia, the Netherlands and Australia turned back on Tuesday, as they were unable to obtain firm commitments from the opposing Ukrainian and pro-Russian rebel forces that the situation would be safe, according to the Australian. The teams, which would inspect the damage to verify if MH17 was shot down and search for any remaining corpses and body parts of the 298 victims, are caught in the unstable region around Donetsk, which is largely the control of the self-proclaimed Donetsk People’s Republic.

“You just have to accept the fact that you don’t go into a fast-moving conflict with a mission like ours,” Special Envoy Angus Houston told the Australian, adding that the situation is “very fluid, very dynamic.”

There are still human remains and machine parts in the isolated field, which could provide basic forensic information about the flight’s final moments. Officials from the Organization for Security and Cooperation and Europe have been trying to negotiate with rebel factions, yet the monitors say all investigations have been postponed until a substantial agreement between the two sides can be reached.

U.S. Secretary of State John Kerry delivered a speech Tuesday in which he called on Moscow, which is believed to have supplied the rebels with the Buk missile that shot down MH17 as well as other arms, to pressure the separatists to maintain the integrity of the crash site.

“The site has to be cordoned off and the evidence needs to be preserved,” Kerry said, adding that Ukrainian forces are willing to accept an immediate cease-fire. “That is the only way this crisis is going to end. What is unfolding in Ukraine has already gone on for too long.”

Journalists reporting from Donetsk and the surrounding area say that, as investigators try to make their way to the area, local residents are fleeing. Families have hunkered down in basement shelters, while neighbors packed up as many of their belongings as would fit into a vehicle and left the area.

“We are in the very center of events,” Lidiya Goryushko, a resident of the tiny Ukrainian village Petropavlovka, told the Washington Post. “We just want to be left alone and to have a quiet life. We don’t want to be touched, and we don’t want our children to be killed.”