The NYPD added extra security around the city Tuesday after terrorists set off bombs at an airport and subway station in Brussels, Belgium. 

Subway stations were among the areas where extra security is being added. 

Extra police security was seen checking commuters' bags inside the subway station at the Atlantic Terminal near the Barclays Center in Park Slope.

The terminal, which also connects to the LIRR, is one of the city's busiest transit hubs. 

Officials said although the attacks in Belgium posed no threat to New Yorkers, they wanted to remain vigilant.

The NYPD said it has added more officers to subway stations around the city as a precautionary measure. 

The Port Authority Police Department said it is also stepped up security at its three major airports.

In addition to more police, the Port Authority said it would deploy anti-terrorism units to patrol the PATH system and World Trade Center sites. 

Mayor Bill de Blasio released a statement saying, "[The] NYPD is on increased alert across our city. While we take this threat seriously, we will not live in fear. Our lives will continue today in honor of those lost to terrorism. Securing New York City is our show of solidarity with the people of Brussels and the victims of terrorism worldwide."