The aircraft was reportedly hit after offloading soldiers at a military base.
Sloviansk has seen fierce fighting between separatists and government forces in recent weeks.
President-elect, Petro Poroshenko has vowed to tackle the uprising in eastern Ukraine, saying he would deal firmly with “bandits” and “murderers”.
There has been an upsurge in the conflict since Mr Poroshenko’s election on Sunday. The rebels say they lost up to 100 fighters when they tried to seize Donetsk airport on Monday.
Since then further clashes have been reported in several areas – including Sloviansk – where pro-Russia militiamen are holding four international monitors.
The Ukrainian Foreign Ministry and the Organization for Security and Cooperation in Europe (OSCE) said that the missing OSCE members were alive and well and there was hope they would be released soon.
“We have not yet been able to re-establish contact with them; it has now been since Monday. Of course, as the days pass we get more concerned but we are using all of our contacts, all our government contacts, diplomatic contacts, non-state actors on the ground of which there are many, to re-establish contact with them.
“We believe they are fine, they are well but of course one thing we do want is to see them return to their base in Donetsk,” Bociurkiw said.
Earlier on Thursday, the leader of pro-Russian separatists in the area where the monitors were seized said they are likely to be released soon.
Vyacheslav Ponomaryov, whose separatist group controls the town of Slaviansk, said the OSCE had been warned not to travel in the area, but had sent a four-man team out all the same.
The team, which comprises a Dane, a Turk, an Estonian and a Swiss, are among a few hundred monitors sent to monitor compliance with an international accord for de-escalating the crisis in troubled eastern Ukraine, where separatists have seized control of strategic points in several towns.