Protesters have been demanding the resignation of Prime Minister Manasseh Sogavare over a host of domestic issues including unrealised infrastructure promises.
Several buildings have been set alight in the Solomon Islands' capital Honiara as thousands of protestors swarmed the city's Chinatown district in a second day of anti-government riots.
Eyewitnesses and local media on Thursday reported crowds had defied a government lockdown to take to the streets.
Live images showed several buildings engulfed in flames and plumes of thick black smoke billowing high above the capital.
The Solomon Islands imposed a 36-hour lockdown on Wednesday in the capital Honiara after protesters calling for the prime minister to resign looted stores and set fire to buildings, including in the Pacific nation's parliament.
Prime Minister Manasseh Sogavare called for the lockdown in an address that was broadcast late on Wednesday, after police had earlier deployed tear gas to break up protests.
People from the country's most populous island, Malaita, had travelled to the capital in a spillover of anger about a host of domestic issues including unrealised infrastructure promises, media reported.
As well as anger about a lack of development, the Solomons government has faced pressure over a 2019 decision to cut ties with Taiwan and establish a formal relationship with China.
"Our nation witnessed another sad and unfortunate event aimed at bringing a democratically elected government down," said Sogavare.
"I had honestly thought that we had gone past the darkest days in the history of our country, however, today's events are a painful reminder that we have a long way to go."
Residents asked to stay indoors
A lockdown in Honiara, which would run until 7am on Friday, local time, "will allow our law enforcement agencies to fully investigate the perpetrators of today's events and to prevent further lawless destruction," he said.
As well as looting stores, demonstrators set fire to a thatched roof building on the grounds of the parliament - as it was sitting - and a police station, said the prime minister.
The Royal Solomon Islands Police Force (RSIPF) urged people attending schools and businesses around Honiara to stay home to avoid being affected by unrest.
"We want to make sure that our streets, schools and businesses will reopen soon after the lockdown," said RSIPF deputy commissioner Juanita Matanga in a statement.
"I am asking for your cooperation until the situation turns normal."