BEIRUT, Lebanon — A convoy of unarmed United Nations monitors got caught up in a violent confrontation between protesters and Syrian government forces on Tuesday, with activist organizations putting the casualty toll at around 20 killed and dozens wounded.

The United Nations monitors escaped unscathed, but three of their four vehicles were damaged by some kind of explosive device, said a statement from Ahmad Fawzi, the spokesman for Kofi Annan, the United Nations and Arab League special envoy for Syria.

Eyewitnesses reached via Skype in Khan Sheikhoun, the town in the embattled northwestern province of Idlib where the confrontation took place, said that a large crowd had turned out for the funeral of a man killed by government forces two days earlier near Hama.

The mourners were surprised when a United Nations convoy rolled into town and headed toward the area where government forces are concentrated, which residents refer to as the Mantiqa, the Arabic word for area.