More death and violence were reported in eastern Ukraine on Sunday, as some investigators stood ready but were unable to go to the crash site of Malaysia Airlines Flight 17, downed more than a week ago.
Many passengers on the plane were from the Netherlands.
At least 13 people, including two children, were killed in fighting on Sunday between pro-Russian rebels and Ukraine government forces in and near the Ukrainian city of Horlivka, according to the Donetsk Regional Authority, citing preliminary information from the local health care department.
Ukraine separatists are using Grad rockets on residential areas of Horlivka, according to Ukraine's Counter-Terrorist Operations Press Center in a statement.
Ukraine's military does not use artillery fire inside city centers to avoid civilian casualties, the statement said. Horlivka is surrounded by government forces.
Pro-Russian militant commander OE Khasanov responded to CNN's Nick Paton Walsh's questions about the attacks in Horlivka by saying that the separatists are defending the city.
Crash site remains 'still under control of terrorists'
The bloodshed comes more than a week after the Malaysia Airlines Flight went down July 17 in eastern Ukraine. All 298 on board were killed.
Though there have been some investigators from the Organization for Security and Co-operation in Europe at the scene, Malaysian investigators haven't been able to access the entire crash site, officials said Sunday.
Malaysia has struck an agreement with pro-Russian separatists in the area to allow international police to protect investigators, Malaysian Prime Minister Najib Razak said Sunday, through a statement from his office. But he said he is "deeply concerned" those investigators still are not on scene due to the "volatile security situation."
He implored that "the human remains are removed from the site, identified and repatriated.
"Everyone who was on board MH17 must be afforded proper dignity and respect," he said. Forty-three passengers on MH17 were Malaysian, including two infants and 15 crew members.
The crash site remains Sunday "still under control of terrorists," Andriy Lysenko, the spokesman for Ukraine's National Security and Defense Council told reporters.
Dutch investigators -- among them a team of 30 forensic experts -- are remaining for the moment in the city of Donetsk, which is about 75 kilometers (50 miles) from Hrabove. About 40 Dutch police officers are also positioned in Donetsk for now.
Russian team ready to join probe
Russia announced it had formed a team to join the investigation, state-run news agency RIA Novosti reported. It will be led by the deputy head of the Federal Air Transport Agency, Oleg Storchevoy.
Russia has continued to increase its military presence near its border with Ukraine, the National Defense and Security Council press office said earlier Sunday. It said two convoys were spotted moving toward a Russian town near southeastern Ukraine.
Ukrainian forces are trying to encircle militants in Horlivka and cut off their communication with Donetsk, the press office said, hours before news emerged Sunday of victims killed in fighting.
The U.S. State Department is putting out photographic evidence to back up U.S. claims that Russian forces have fired across the border at Ukrainian military forces, and that Russia-backed separatists have used heavy artillery provided by Russia in attacks on Ukrainian forces from inside Ukraine.