Former President Donald Trump attended the wake of a New York City police officer who was fatally shot during a traffic stop on Monday.
Officer Jonathan Diller died after the occupant of an illegally parked car opened fire on him.
"We have to stop it. We have to get back to law and order," Mr Trump said outside the Long Island funeral home, after meeting the Diller family.
He has sought to make crime a key issue in his presidential campaign.
Mr Trump and other Republican figures have regularly accused Democrats of being weak on crime. The former president emphasised this view when he exited Mr Diller's wake flanked by about a dozen police officers.
"We have to do a lot of things differently because this is not working. This is happening too often," Mr Trump told reporters.
President Joe Biden, a Democrat who Mr Trump is challenging for the White House, was in New York at the same time as his predecessor. He is attending a large fundraiser on Thursday evening at Radio City Music Hall in Manhattan. The event was set to feature former presidents Barack Obama and Bill Clinton and numerous celebrity guests.
The fundraiser is expected to bring in $25m (£19.8m) for Mr Biden's re-election effort, his campaign said.
Mr Trump, who faces 91 felony charges across four criminal cases, and his staff sought to draw a contrast between the two visits.
Mr Trump will be "honouring the legacy of Officer Diller" while Mr Biden "will be at a glitzy fundraiser in the city with their elitist, out-of-touch celebrity benefactors," Trump campaign spokesman Steven Cheung wrote on X, formerly Twitter.
White House spokesperson Karine Jean-Pierre told reporters on Thursday that Mr Biden had spoken with Mayor Adams and offered the administration's condolences to Mr Diller's family.
"Violent crime surged under the previous administration," Ms Jean-Pierre told reporters aboard Air Force One, the Associated Press reported. "The Biden-Harris administration have done the polar opposite, taking decisive action from the very beginning to fund the police and achieving a historic reduction in crime."
The White House spokesperson previously said at a briefing that Mr Diller's death is a "painful reminder of the toll of gun violence", which she said is an issue that the administration has worked to address.
Mr Diller's killing, which occurs as a debate over public safety and crime has developed in some major US cities, is the first of a New York City police officer since 2022.
Authorities have charged 34-year-old Guy Rivera with first-degree murder of a police officer.
Mr Rivera is accused of shooting Mr Diller from a car that was illegally stopped at a bus stop. The policeman had tried to order the occupants to get out of the vehicle when he was shot under his bulletproof vest, the New York Police Department said.
Mr Diller later died at hospital, and his death has further ignited the view - particularly among Republican voters - that crime is a growing problem in New York City.
New York Police Department data shows crime has decreased by about 1% over the past two years.