BEIRUT — Hundreds of Syrians, some of them with gunshot wounds, streamed into neighboring Lebanon on Saturday in search of a refuge from the increasing violence in their homeland, a Lebanese security official said.

The arrivals at the border began shortly after Syrian security forces opened fire on anti-government protesters across the country, killing 20 people, including two children aged 12 and 13, Syrian activists said.

The violence has prompted thousands of Syrians to seek a safe haven in neighboring countries.