President Donald Trump used a shooting that French authorities say was terrorism to call on Democrats to fund his desired wall along the US-Mexico border.

A gunman in the northeastern French city of Strasbourg killed two people, left one brain-dead, and injured 13 others near a Christmas market on Tuesday night.

Earlier Tuesday, Trump engaged in a heated, televised debate with the Democratic leaders Nancy Pelosi and Chuck Schumer in the Oval Office.

The president told the pair he would be "proud" to shut down the government if they didn't help him fund the wall.

President Donald Trump used Tuesday night's shooting in France to call for the Democratic leaders Nancy Pelosi and Chuck Schumer to agree to fund construction of a wall on the southern US border.

"Another very bad terror attack in France," Trump tweeted on Wednesday morning. "We are going to strengthen our borders even more. Chuck and Nancy must give us the votes to get additional Border Security!"

A gunman killed two people, left one brain-dead, and injured 13 more in the northeastern French city of Strasbourg on Tuesday night. The French police have determined the attack was terrorism.

The French police had listed the suspect in the shooting as a potential terror threat, The Guardian reported, and witnesses said the attacker had shouted "Allahu Akbar," Arabic for "God is great." After searching for the suspect all night, French authorities believe he may have fled the country.

Read more: Strasbourg suspect may have escaped France after 14-hour manhunt

Earlier Tuesday, Trump had engaged in a heated showdown with Pelosi and Schumer in the Oval Office over his long-promised wall along the US-Mexico border.

Pelosi, the House minority leader, and Schumer, the Senate minority leader, confronted Trump over his repeated false claims, urging him to have a "truthful" discussion.

At one point in his remarks, Trump boasted that "a lot of the wall is built" and that "it's been very effective," though only prototypes have been built so far. Pelosi urged him to have an "evidence-based conversation."

Trump with Pelosi and Vice President Mike Pence in the Oval Office on Tuesday. Mark Wilson/Getty Images

Pelosi last week shot down negotiations that would include funding for Trump's long-desired wall. She said funding for what she called the "immoral, ineffective, expensive" wall was off the table.

Read more: Trump inexplicably told Chuck Schumer and Nancy Pelosi that Mexico would pay for the border wall as part of the landmark new trade deal

On Tuesday, Trump said he'd be "proud to shut down the government" if Democrats didn't help him gain funding for the wall.

"I am proud to shut down the government for border security," he said.

"So I will take the mantle. I will be the one to shut it down. I'm not going to blame you for it — the last time you shut it down, it didn't work. I will take the mantle of shutting it down. And I'm going to shut it down for border security."