Video captures concertgoer being kidnapped by militants.

Videos verified by The New York Times show a woman — an attendee at a music festival that fliers said celebrated “free love” — being kidnapped by what appear to be militants on Saturday during a wave of ground incursions into Israel from Gaza.

The footage, which was posted to Telegram, showed a group of men driving away on a motorcycle with 25-year-old Noa Argamani in their custody. The video then pans to another group of militants holding Ms. Argamani’s boyfriend, Avinatan Or, with an arm pinned behind his back.

A family member of Ms. Argamani confirmed to The Times that the video shows both her and Mr. Or. Moshe, Mr. Or’s brother, also shared screenshots of the video on Instagram, identifying both his brother and Ms. Argamani.

The weekend-long event, billed as a “psy trance music festival,” was attended by about 3,500 people near Re’im, Israel, three miles from the border with Gaza. Israeli security officials said up to 109 people were believed to have been killed at the festival.

The festival’s organizer, Nimrod Arnin, told The Times that around 6:30 a.m. Saturday, a rocket barrage from Gaza began, prompting an evacuation of the festival. Videos show concertgoers walking to their cars as puffs of black smoke rose in the sky.

Militants soon swept into the area, turning what had been a calm evacuation into a scene of panic and sprinting. Videos showed attendees fleeing south over fields and into a valley and a wooded area.

Mr. Or and Ms. Argamani had been trying to hide from the militants before being taken hostage. According to WhatsApp messages posted on Facebook, Mr. Or shared his location with a friend and pleaded for Israeli soldiers to come rescue them.

“Me and Noa are hiding here,” Mr. Or wrote. “Tell them there’s a gang of 20 men that are finding people who are hiding and lynching them.” He stopped responding around 10 a.m., the messages show.

Ravid Ohad, Ms. Argamani’s cousin, told The Times that family members were able to trace her location to Gaza, as of around noon on Saturday, using the Find My iPhone application, but haven’t received further information about her location or her captors.

“It’s still not too late to save my brother and Noa,” wrote Mr. Or’s brother Moshe in an Instagram post. “Israel state must act! Fast!”

Another video that surfaced online Saturday showed Ms. Argamani purportedly in captivity in Gaza wearing the same clothes she had on when she was abducted. A family member confirmed it was her in the video. The Times could not independently verify her location.

Appeals posted on social media asked people who attended the festival to report sightings of loved ones who have been out of touch since the attack.

In a statement posted on Instagram, the festival organizers said they were doing “everything in their power to assist the security forces.” They added that festival staff members are carrying out “scans and searches in order to locate the missing.”

Dahlia Kozlowsky contributed reporting from New York.