The NYPD increased security at mosques in the city, following a shooting at a mosque in Quebec City that killed six people and wounded 19 on Sunday, police said.

“Critical Response Command personnel have been assigned to extended tour coverage at certain mosque locations,” the NYPD said in a statement. The agency added it is monitoring the situation in Quebec while working with the FBI Joint Terrorism Task Force.

"As of now, there is no specific credible threat to New York City. The NYPD continues to patrol sensitive locations throughout NYC," the NYPD said in a statement Monday afternoon.

Canadian police said two suspects were arrested after the attack, which Prime Minister Justin Trudeau called a “terrorist attack on Muslims.” By Monday afternoon, authorities said they were only investigating a single suspect and that the other man was now considered a witness to the shooting.

Mayor Bill de Blasio tweeted Sunday night, asking New Yorkers to be vigilant.

In another tweet, de Blasio wrote that New York City and the NYPD will protect Muslims. “We will fight all hatred an bias,” the mayor said.

Prior to the shooting, Trudeau said Canada would welcome refugees after President Donald Trump put a temporary ban on citizens, including refugees, from seven Muslim-majority countries.