Belgian security forces patrol on the streets in Brussels, Belgium, on Nov. 21, 2015. Dursun Aydemir/Anadolu Agency/Getty Images

Streets and large markets were largely deserted in Belgium’s capital Brussels on Sunday as the city stayed on maximum alert for the second day amid fears of Paris-style coordinated attacks.

Since late Friday, Brussels residents were told to avoid crowded places. The metro was closed, and cinemas, shopping malls, cafes and restaurants were asked to shut at 6 p.m., according to reports.

The Crisis Centre of the Belgian Interior Ministry, which advises the government on security, cited "a serious and imminent threat" when it announced Friday evening that the capital's terror alert level was being raised to 4, the highest in the country.

However, according a Reuters report, Brussels retained a sense of normalcy, as small shops and supermarkets stayed open and many churches held Sunday services.

Belgium has been at the center of a massive investigation into the Nov. 13 Paris attacks after it emerged that some of the attackers had links to Brussels and the poor district of Molenbeek.

Soldiers patrolled the streets of Brussels on Sunday as a manhunt continued for the fugitive Salah Abdeslam, brother of one of the Paris suicide bombers Brahim Abdeslam. Abdeslam is said to have slipped into Brussels shortly after the attacks that left 130 people dead.

Friends of Salah told ABC News that they had spoken to him on Skype Tuesday and said he was hiding in Brussels and desperately trying to get to Syria.

The Belgian authorities have so far charged three people with involvement in the Paris attacks, according to BBC.

While investors try to piece parts of the evidence to gather a full picture about those responsible for planning and executing the Paris attacks, Turkey arrested a Belgian citizen of Moroccan origin named Ahmad Dahmani, suspected to have links to ISIS.

Dahmani, 26, is accused of being "in contact" with the Islamist extremists who carried out the attacks in the French capital and was arrested Saturday along with two others trying to cross the border into Syria.