Bolivarian National Police fire tear gas toward opposition demonstrators in Caracas, Venezuela, Saturday, Feb. 15, 2014. Venezuelan security forces backed by water tanks and tear gas dispersed groups of anti-government demonstrators who tried to block Caracas' main highway Saturday evening. (AP Photo/Alejandro Cegarra)
An opposition protester stands in silence with her arms painted with the words in Spanish "To create freedom" during a protest in Caracas, Venezuela, Saturday, Feb. 15, 2014. Demonstrators are protesting the Wednesday killings of two university students who were shot in different incidents after an anti-government protest demanding the release of student protesters arrested in various parts of the country. (AP Photo/Fernando Llano)
Demonstrators block a road with chairs as others throw stones at National Bolivarian Police (BNP) in Caracas, Venezuela, Saturday, Feb. 15, 2014. Venezuelan security forces backed by water tanks, tear gas and rubber bullets dispersed groups of anti-government demonstrators who tried to block Caracas' main highway Saturday evening. (AP Photo/Fernando Llano) (AP2014)
A masked opposition demonstrator holds up a poster that reads in Spanish "Ideas are bullet proof! Freedom always!" at a protest in Caracas, Venezuela, Saturday, Feb. 15, 2014. Demonstrators are protesting the Wednesday killings of two university students who were shot in different incidents after an anti-government protest demanding the release of student protesters arrested in various parts of the country. (AP Photo/Fernando Llano)
Opposition demonstrators shout slogans against the National Bolivarian Police in Caracas, Venezuela, Saturday, Feb. 15, 2014. Venezuelan security forces backed by water tanks, tear gas and rubber bullets dispersed groups of anti-government demonstrators who tried to block Caracas' main highway Saturday evening. (AP Photo/Alejandro Cegarra)
National Bolivarian Police officers yell at demonstrators to leave in Caracas, Venezuela, Saturday, Feb. 15, 2014. Venezuelan security forces backed by water tanks, tear gas and rubber bullets dispersed groups of anti-government demonstrators who tried to block Caracas' main highway Saturday evening. (AP Photo/Alejandro Cegarra)
A demonstrator affected by tear gas, fired by the Bolivarian National Police, is helped after an opposition protest ended in clashes in Caracas, Venezuela, Saturday, Feb. 15, 2014. Venezuelan security forces backed by water tanks, tear gas and rubber bullets dispersed groups of anti-government demonstrators who tried to block Caracas' main highway Saturday evening. (AP Photo/Fernando Llano)