Chamlong Srimuang, a former army general who is one of the protest leaders, met with the chief of police in Bangkok to request that police officers join protesters in patrolling the besieged prime minister’s office, where the explosion took place, Thai media reported.

The meeting came amid growing fears of violence between protesters and government supporters, who held a demonstration Sunday in the heart of Bangkok.

But the meeting between Chamlong and the police also underlined the demonstrators’ impunity in carrying out their illegal sit-ins, which have stranded more than 100,000 travelers both inside Thailand and in neighboring countries that rely on Bangkok as a hub.