PORTLAND, Ore. — Investigators found pro-Palestinian messages on the devices used to burn ballot boxes in both Portland and Vancouver, the New York Times reported Tuesday. The Times did not identify their sources, saying that two law enforcement officials confirmed the discoveries.

Early Monday morning, an incendiary device burned hundreds of ballots within a box in Vancouver near the Fisher's Landing Transit Depot. Another device burned a ballot box outside the Multnomah County Elections Division in Portland, but a built-in fire suppression device limited the damage to just three ballots.

Police have linked those two arsons to a similar attempt in Vancouver on Oct. 8, when police and firefighters found a "suspicious device" burning on a ballot box on Esther Street. That incident did not damage or destroy any ballots.

Portland police have shared stills of a suspect vehicle believed to be connected to all three incidents, described as a black or dark-colored 2001-2004 Volvo S-60 with no front license plate and an unknown rear plate.

READ MORE: Hundreds of ballots destroyed in drop box arson; officials say Vancouver, Portland incidents linked

According to the Times' reporting Tuesday, similar messages saying "Free Gaza" and "Free Palestine" appeared on all three devices. However, the newspaper reported that investigators were still trying to determine whether the suspect could indeed be a pro-Palestinian activist or someone trying to misdirect police and cause chaos ahead of the election.

The U.S. Department of Homeland Security has issued warnings about people online talking about ways to target ballot boxes, according to a brief obtained by watchdog group Property of the People.

In one memo, DHS said, "election infrastructure remains an attractive target for some domestic violent extremists," and "states with more ballot drop boxes may be more at risk."

According to the Times, investigators have sent all three devices to the terrorist explosive device analytical center in Huntsville, Alabama.

After firefighters extinguished Monday morning's ballot box fire in Vancouver, the smoking and rain-dampened ballots were collected and brought back to the Clark County Elections office, where officials have been looking to recover what they can.

"We are still drying those out, we are not yet ready to really begin processing those damaged ballots," said Clark County Auditor Greg Kimsey.

According to Kimsey, many people are reaching out for replacement ballots and checking to see if their ballots were impacted by the fire. He told the Associated Press that about 475 damaged ballots were retrieved from the burned ballot box.

READ MORE: Here's what to do if you think your ballot was destroyed in Washington, Oregon ballot box fires

The county has since replaced the burned ballot box and has hired contract workers to watch all 22 drop locations through Election Day.

On Tuesday, it was Jennifer Whitaker stationed near an east Vancouver ballot box, vigilantly watching for anything out of the ordinary.

"I really care about what happened yesterday and wanted to help protect democracy," Whitaker said.

READ MORE: New security measures in place after ballot box fires in Vancouver and Portland

The fact that people like her have been hired to watch the boxes has reassured Whitaker that, at the very least, this isn't being ignored.

"It made me think that they take this very seriously, that it wasn't just like, 'Oh well, that happens,'" she said. "They literally immediately decided to protect the ballots."