A woman told the San Francisco Chronicle she saw a group of young men harassing the big cats on Christmas Day shortly before a tiger escaped and mauled them.

Jennifer Miller told the paper she was at the zoo with her husband and two children.

Video: SF Zoo Reopens For First Time Since Tiger Attacks | SLIDESHOW: NBC11 Goes Inside The SF Zoo After Tiger Attack
She said there was a group of four young men and that three of them were teasing the lions.

"The boys, especially the older one, were roaring at them. He was taunting them," Miller told the paper.

She said she left the area because the group's actions were disturbing her children.

She said the teenager who died, Carlos Sousa Jr., was not taking part in the heckling.

Miller said the group stood out because there were mostly families at the zoo on Christmas Day.

Miller said she reported what she saw to San Francisco police. Miller said there were four young men in the group, but police have said from the beginning that only three people were in the group that were mauled by the lion.

The zoo reopened Thursday at 10 a.m. with a new public address system to notify visitors if a dangerous animal escapes, Mollinedo said.

Visitors will also be greeted with signs throughout the zoo about "proper zoo etiquette," warning against tapping on glass enclosures, throwing objects into exhibits, making excessive noise, and teasing or calling out to animals.

On Wednesday, the director of the San Francisco Zoo said the tiger that escaped and killed a zoo visitor and injured two others on Christmas Day was provoked before it leaped over its enclosure, though he declined to point the finger directly at its victims.

"Something prompted our tiger to leap over the exhibit," zoo director Manual Mollinedo said Wednesday afternoon at a news conference announcing new security measures for the zoo's reopening Thursday, the first time since the fatal mauling.

Mollinedo would not say whether he felt any of the three friends attacked outside the big cat exhibit on the afternoon of Dec. 25 were acting improperly toward Tatiana, a 350-pound Siberian tiger. The tiger somehow traversed a 33-foot-wide moat, scaled a 12-foot, 5-inch high wall, and fatally mauled Sousa Jr., of San Jose.

"All I know is that something happened to provoke that tiger out of the exhibit," Mollinedo repeated.

A police investigation into the incident is still ongoing.

Two of Sousa's friends, San Jose brothers Paul Dhaliwal, 19, and Kulbir Dhaliwal, 23, according to media reports, were also attacked, hospitalized and treated for claw and bite wounds. Police responding to the zoo fatally shot the tiger.

About 20 visitors were still inside the zoo at the time of the tiger escape, as the zoo was closing around 5 p.m., according to Mollinedo.

The big cat exhibit remains closed indefinitely while the zoo constructs a higher wall around the exhibit's grotto area. Mollinedo said the current wall will be extended to 19 feet and will include glass portals for visitors to view the cats.

Construction on the wall is expected to take about 30 days, he said. The zoo also has "long-term" plans to install security cameras, Mollinedo said.

"I want to ensure all our visitors that the zoo is a safe place," Mollinedo said.

San Francisco Mayor Gavin Newsom told NBC11 he spent much of Wednesday at the zoo.

He said the zoo's future is in jeopardy.

"Can we improve things? Yes. They admit that first thing first -- secure lions and tigers before you put them back in those areas so people feel safe and confident so we don't bleed financially. That's something we're all worried about," Newsom said.

Newsom called the attack tragic because, he said, a 17-year-old was killed.