SANAA, Yemen - A Yemeni activist says security forces have fired on anti-government protesters in southern Yemen, killing two people.

Nouh al-Wafi says one protester was killed and four wounded in the flashpoint city of Taiz and another protester was killed in the city of Damar after demonstrators calling for the ouster of longtime President Ali Abdullah Saleh clashed with police Wednesday.

Also, protesters in the capital have started a second sit-in on one of the city's main streets. This adds to the already large permanent sit-in on Change Square near Sanaa University.

Organizers also are considering marching on the presidential palace despite the heavy security around it to press Saleh to step down.

More than 140 people have reportedly been killed in the government crackdown on the escalating protests.