BANGKOK?- Bangkok's emergency services center says 22 people were injured when an explosion hit marching anti-government protesters in the capital.

Protest spokesman Akanat Promphan said the movement's leader, Suthep Thaugsuban, was in the procession Monday but was not wounded.

Akanat said an explosive device was thrown into a truck driven by demonstrators that was several dozen meters (yards) ahead of Suthep.

Protesters trying to oust Yingluck Shinawatra have marched peacefully across the capital this week.

But small acts of violence have been reported nightly at protest venues, which have been targeted in shooting attacks and with small explosives hurled at the homes of top supporters.