Gun battles have broken out between the military and protesters inside the Red Shirts' rally base in central Bangkok, with at least five people killed in the violence.
Police have confirmed they have authorised troops to "shoot immediately" people inciting unrest.
Reports coming out of Thailand also note journalists have come under attack, with a Bangkok hospital confirming an Italian man has died from wounds sustained in the violent clashes.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
A Thai Senator says anti-government protest leaders will surrender shortly, as reports suggest a number of Red Shirt leaders have fled the scene.
Troops have entered the base backed by armoured personnel carriers and a reporter says he's seen the bodies of two men with bullet wounds.
The reporter followed troops who punched a hole through the protest encampment's barricade in a major assault after seven days of clashes that have left at least 39 people dead.
Both sides firing
Gunfire was being exchanged from both sides and at least one Red Shirt protester was seen carrying a weapon, after security forces broke through barricades and pushed inside the rally base on Wednesday.
An Agence France-Presse photographer saw two people shot and lying motionless on the ground inside the camp. At least seven other protesters have been injured and sent to hospital.
In the face of the barrage, some 100 other protesters fled towards the movement's main rally stage in their heart of their encampment in Bangkok's main shopping district, which they have occupied for six weeks.
