WARSAW, Poland (AP) — Police say that protesters in Poland threw balloons with red paint at the headquarters of the ruling conservative Law and Justice party, leaving some marks on the building.

The incident occurred late Wednesday after hundreds of people, mostly women, marched through Warsaw calling for a liberalization of the country's abortion laws. Similar protests occurred in other cities too.

Police spokesman Mariusz Mrozek said about 11 paint-filled balloons were thrown against the party building in central Warsaw, but that not all burst open.

Private broadcaster TVN showed images of red paint on the outside of the building.

Protesters are angry that parliament is considering tightening the country's abortion law, which is already one of the most restrictive in Europe.