Protests in Bangkok boiled over yesterday. For the first time since the shutdown began, riot police with shields and batons tried to clear protest sites in the capital, including at the Ministry of Energy and the Interior Ministry. (Here's a map of current protest areas.)

Police and protesters exchanged gunfire, while tear gas and at least one grenade was thrown (here's AFP's raw footage of the crackdown). Four people were killed and 64 injured in the clashes. At least one of the dead has been identified as a police officer and 10 of the injured are reported to be police.

Social media was abuzz with images and videos of the protests on Monday. The BBC's Jonathan Head posted raw footage of a grenade being thrown at policemen (graphic content). And photos of the wounded and small arsenals of weapons seized by police also circulated widely, adding fuel to a protest that has drawn much support from social media.

The crackdown came a day before the Civil Court is due to rule on the legality of the emergency decree which has allowed the detention of protesters and protest leaders for up to 30 days without charge. The repealing of the decree would be a blow to Prime Minister Yingluck Shinawatra's caretaker government and her attempts to tackle protests. 

Most importantly however, the escalation on the streets was matched by the National Anti-Corruption Commission (NACC). The anti-graft body on Monday charged the caretaker PM for alleged negligence and dereliction of duty over the controversial rice subsidy plan. The charges could initiate impeachment proceedings. On 27 February she will hear the charges and if the NACC decide to submit the case to the Senate she will be suspended immediately from all official duties while awaiting trial.

The rice subsidy scheme has long been criticised by economists and commentators. Prime Minister Yingluck Shinawatra appeared on national television on Monday before the crackdown defending the controversial scheme that has seen many of her supporters, mainly farmers, protest against her, escalating the crisis in recent weeks.

As Yingluck battles on, Suthep Taungsuban, leader of the protesters, once again declared on Monday evening that there would be 'no more negotiation' with Shinawatra. If she were to face impeachment, it would legitimise his campaign, which has now run for over 100 days, and further uphold his hero status in the eyes of protesters.

Figures released Monday showed growth in the economy slowed to 0.6% in the final quarter of 2013, down from 2.7% the previous quarter, and growth targets have been downgraded for 2014.  As the economy continues to be hit hard, many Thais and foreign businesses are growing impatient. It is therefore worrying that, with the potential removal of Yingluck as early as next week, Suthep's plans if he were to somehow wrestle the top job remain so fluid, so unconstitutional and so undemocratic.

By-elections are now due to be held on 20 April and a re-run of voting in constituencies that were disrupted by protests in southern Thailand will happen a week later.

As the military noted early on in the life of the protests, only if there was an escalation of violence would it step in. Monday marked a significant escalation. Yet there is little appetite for a coup within the military. It would also not likely be seen favorably by the King-in-waiting, as the Prince allegedly has close ties to the Shinawatra family.

So the removal of Yingluck through impeachment may just drag this sorry saga deeper into despair. It would create a power vacuum until the April by-elections. And even then, Yingluck's Pheu Thai party is tipped to win.