FBI officials on Sunday said their investigation into the deadly truck attack in New Orleans is now "crossing state and international borders" and that the attacker had travelled to both Egypt and Canada.

Shamsud-Din Jabbar, a U.S. citizen from Houston, travelled to Egypt and Canada before the New Year's Day attack, although it was not yet clear whether those trips were connected to the attack, Christopher Raia, the agency's deputy assistant director, said at a news conference.

Jabbar travelled to Cairo from June 22 to July 3, 2023. A few days later, he flew to Ontario on July 10 and returned to the U.S. on July 13.

"Our agents are getting answers to where he went, who he went with and how those trips may or may not tie into his actions here," said Lyonel Myrthil, FBI special agent in charge of the New Orleans field office.

Canadian Minister of Public Safety David McGuinty confirmed in a statement on Sunday that Jabbar travelled to Canada in July 2023, noting he arrived from Houston, not Cairo.

"Canadian authorities will continue to work with their American counterparts, including the FBI, as they pursue their investigation," McGuinty said.

In a statement to CBC News, the RCMP said it is "engaged with security partners, including U.S. authorities, as part of the investigation in this case."

Jabbar had also travelled to New Orleans twice in the months preceding the attack, first in October and again in November. On Oct. 31, Myrthil said, Jabbar used glasses from Meta, the parent company of Facebook, to record video as he rode through the French Quarter on a bicycle as "he plotted this hideous attack." He said Jabbar was also in New Orleans on Nov. 10, and authorities are seeking more details about that trip.

He also wore the glasses capable of livestreaming during the attack, but Myrthil said Jabbar did not activate them.

The FBI released Jabbar's recorded video from the planning trip to New Orleans, as well as video showing him placing two containers with explosive devices in the French Quarter at about 2 a.m., shortly before the attack. One of the containers, a cooler, was moved a block away by someone uninvolved with the attack, officials said.

Investigators previously said Jabbar, a 42-year-old former U.S. army soldier, had proclaimed his support for the Islamist militant group ISIS in online videos posted hours before he struck on Bourbon Street early last Wednesday, killing 14 people and injuring dozens. Police fatally shot Jabbar during a firefight at the scene.

Thirteen people remain hospitalized after the attack.

Raia reiterated on Sunday that the FBI believes Jabbar acted alone.

"All investigative details and evidence that we have now still support that Jabbar acted alone here in New Orleans," Raia said. "We have not seen any indications of an accomplice in the United States, but we are still looking into potential associates in the U.S. and outside of our borders."

U.S. President Joe Biden planned to travel to New Orleans with his wife, Jill Biden, on Monday to "grieve with the families and community members impacted by the tragic attack."

The youngest victim was 18 and the oldest 63. Most victims were in their 20s. They came from Alabama, Louisiana, Mississippi, New York, New Jersey and Britain.

Louisiana Gov. Jeff Landry said the innocent lives lost will never be forgotten as he declared a period of mourning for the victims that is scheduled to begin on Monday. A different victim is to be remembered each day.

"However, Louisiana and her people will never cower in fear," he said. "Instead, we will unite and come back stronger in honour of every person who lost their lives that day."