Venezuelan student protest in capital ends in clashes

Security forces in Venezuela have used tear gas to break up a student demonstration in the capital, Caracas. Hundreds of protesters were demanding the release of fellow students detained during two weeks of unrest, and called a fresh march for Sunday. In another part of Caracas, a large pro-government march was held.
Background:
Venezuela student protest in Caracas ends in clashes [BBC]
Opinion: Venezuela's angry students [NYT]
Venezuela protests to blame for 50 deaths, says Maduro [BBC]
Unrest shakes up oppo [Reuters]