Near Mariupol, Ukraine (CNN) Five Ukrainian security forces were killed and 22 wounded in fighting with pro-Russian separatists after a ceasefire between the two sides went into effect at midnight Saturday, a Ukrainian army spokesman told CNN Monday.

Mortar fire has been coming into the Mariupol area, said Dmyto Chalov, spokesman for a sector of the Ukrainian army.

The Ukrainian Army still has plans to pull heavy weapons out of the area, but it will happen until the situation is quiet, Chalov said.