TRIPOLI, Libya – The protesters converged on the conference center housing Libya’s newly elected congress, trying to force their way in past startled guards. Mostly young and half of them women in headscarves, they demanded an end to the siege of the town of Bani Walid, where the government was in the midst of an attack to uproot holdouts from Moammar Gadhafi’s former regime.

Police rushed to the scene. But in Libya, the police are actually militias, in this case from the Tripoli neighborhood of Souq al-Jumaa that last year lost several men in a battle with Bani Walid residents.

Instead trying to control the crowd, the “police” dressed in T-shirts and pants of a military uniform exchanged threats with protesters and then mounted a rival demonstration of their own. Soon they were firing their assault rifles in the air to intimidate the protesters.