Police have conducted new raids in Brussels in an operation a local official said was linked to both the attacks in Belgian capital and to the arrest in Paris of a man who may have been plotting a new attack in France.

Three people were detained, two of them shot in the leg, the federal prosecutor's office in Brussels said following the raids on Friday.

Belgium's state broadcaster RTBF said one person who was detained was carrying a bag of explosive materials.

WATCH: Why was Brussels attacked?

The operation was conducted in the Schaerbeek district as well as the Forest and Saint-Gilles neighbourhoods. Schaerbeek was also raided Thursday night, and six people were initially detained for questioning, before three of them were eventually released.

Schaerbeek district Mayor Bernard Clerfayt told RTBF that the raids were linked to the Brussels attacks and Thursday's detention of Reda Kriket, a man in France who was convicted in absentia of "terrorist activities" last year.

At least two explosions were heard in Schaerbeek at the start of the operation on Friday.

Al Jazeera's Dominic Kane, reporting from the Schaerbeek, said the explosions he heard during the raid were consistent with the sound of stun grenades, usually used by police during raids.

Images captured by Al Jazeera in Schaerbeek showed armed police officials and security personnel donning special suits crowding near Place General Meiser, an area with mixed residential and business establishments.

As the raid was carried out, US Secretary of State John Kerry placed a wreath at a memorial at Zaventem airport for the victims of the Brussels attacks.

Kerry is in Brussels for security talks with the country's and EU officials in the wake of the deadly attacks that left 31 dead.

Earlier, the US secretary of state pledged further US help to Belgium and the EU after his meeting with Belgian Prime Minister Charles Michel, Foreign Minister Didier Reynders and Jean-Claude Juncker, head of the EU executive body based in Brussels.

"The United States is praying and grieving with you for the loved ones of those cruelly taken from us, including Americans, and for the many who were injured in these despicable attacks," Kerry said.

On Friday evening, hundreds of people gathered in central Brussels to pay tribute to the victims.

Suicide bombers hit the Brussels airport and a metro train on March 22, killing 31 people and wounding at least 270 in the worst such attack in Belgian history.

The Islamic State of Iraq and the Levant (ISIL, also known as ISIS) group, which claimed responsibility for the Brussels bombings, also took credit for coordinated attacks in Paris in November which killed 130 people.