Two senior UN officials -- UN Under-Secretary General Jeffrey Feltman and humanitarian aid chief Valerie Amos -- will travel to Kiev later this week amid an upsurge in fighting in east Ukraine.
Ban urges all sides to "allow safe passage to anyone attempting to leave areas of active military operations," his spokesman said.
"This tragic incident makes the urgency of a ceasefire and a diplomatic solution even more stark," he said.
Foreign ministers from France, Germany, Russia and Ukraine failed during talks on Sunday to make progress in ending the conflict that has killed more than 2,100 people since April.