Sri Lankan Prime Minister Mahinda Rajapaksa resigned as his loyalists went on rampage today, injuring more than 100 anti-government protesters in Colombo. 

The loyalists had attacked unarmed protesters camping outside the President’s office in downtown Colombo since April 9.

In the process a ruling party MP was killed in the clashes, many were hospitalised.

In a first, the riot squad was called in to reinforce the police. Earlier, soldiers were pressed into service to protect deliveries of fuel and other essentials but never to prevent clashes.

At least 100 injured people have been hospitalised, police sources have said.

The police fired tear gas shells and water cannon and declared an immediate curfew in Colombo, which was later widened to span the country of 22 millon people.

Ruling party MP Amarakeerthi Athukorala opened fire and critically wounded two people blocking his car in Nittambuwa, and was later found dead after trying to take refuge in a nearby building, officers said.

Mr Rajapaksa, 76, had sent his letter of resignation to his younger brother, President Gotabaya Rajapaksa, clearing the way for a “new unity government”.

“I am resigning with immediate effect so that you will be able to appoint an all-party government to guide the country out of the current economic crisis,” the Prime Minister said in the letter, reported news agency AFP.

The cabinet now stands dissolved. The largest opposition party has refused to join any government headed by a member of the Rajapaksa clan.

Sri Lanka has suffered months of blackouts and dire shortages of food, fuel and medicines in its worst economic crisis since independence, sparking weeks of overwhelmingly peaceful anti-government demonstrations.