Here's your 10-point cheatsheet to this big story:
The curfew has been imposed to prevent protests and Sri Lankans won't be allowed to step out unless for essential services during the curfew.
The Sri Lankan government has also blocked access to all social media sites, including Facebook, Twitter, Instagram, WhatsApp and YouTube, in an attempt to stem misinformation and to disallow people from mobilising crowd to orchestrate protests in the country.
The nation of 22 million people is in the grips of its worst downturn since independence, sparked by an acute lack of foreign currency to pay for even the most essential imports.
Diesel -- the main fuel for buses and commercial vehicles -- was unavailable at stations across the island, according to officials and media reports -- crippling public transport.
Owners of private buses -- which account for two-thirds of the Sri Lanka's fleet -- said they were already out of oil and that even skeleton services might not be possible after today.
Indian traders have started loading 40,000 tonnes of rice for prompt shipment to Sri Lanka in the first major food aid since Colombo secured credit line from New Delhi, two officials told Reuters on Saturday.
A consignment of 40,000 metric tonnes of diesel from India reached Sri Lanka on Saturday, the fourth such assistance from New Delhi, to mitigate the spike in power cuts in the island nation. Power cuts lasting over 13 hours were imposed on Thursday, the longest cut since 1996 when a strike by the state power entity employees caused a 72-hour black out.
Sri Lanka's President Gotabaya Rajapaksa declared a state of emergency on Friday, giving sweeping powers to security forces. The country's former president Maithripala Sirisena's Freedom Party has called on President Gotabaya Rajapaksa to form an all-party government to tide over the crisis, news agency PTI reported.
Mr Rajapaksa invoked the tough laws allowing the military to arrest and detain suspects for long periods without trial as demonstrations calling for his ouster spread across the island nation.
The southern towns of Galle, Matara and Moratuwa also saw anti-government protests, and similar demonstrations were reported in the northern and central regions. All held up traffic on main roads.