According to this report Thai protesters have stormed Parliament, causing ministers to flee by helicopter. The Prime Minister has declared a state of emergency, which authorizes authorities to ban public gatherings of more than five people and suspend certain civil liberties. Still, police did not appear to be using force against the Red Shirts. Out of self-preservation motives and to ensure that the situation does not become worse, the government has shown considerable restraint during the weeks-long protests.
UPDATE (4/10): This report indicates that military forces pushed back against the protesters, but ultimately avoided a full-scale confrontation.
UPDATE II (4/11): And this report indicates that things have taken a violent turn, with 18 dead and more than 650 wounded. It appears that protesters went on the offensive and that the military was then forced to respond. Soldiers were eventually ordered to retreat. It is not clear where negotiations between the Red Shirts and the Prime Minister stand. The protesters continue to demand his ouster, and the Prime Minister continues to offer only earlier elections. The mostly successful clashes with soldiers will likely embolden the protesters.