Friday's disastrous events happened on Paris put American people in great fear. Every people in New York have imagine how the  tremor of terror that struck Paris on Friday might penetrate American lives too.

Parents and relatives of teenagers warned them to stay out of huge crowds and pay attention to feelings of threats. Families think of whether a Saturday trip or weekend escape will still make sense.

In Manhattan hotel, a young woman from South Carolina prayed over for the victims whom she said most likely are concert-goers, diners at fashionable restaurants and soccer fans.

Almost all of them felt unsafe, they were shaken by a threat from extremists whose planning a new assault on the most crowded places of the city. Danger now lie in wait to perform their routines, stalking urban areas.

"I couldn't take the subway home last night because I felt like, 'What if?' ", stated by Aba Obieshi, 19, a music student in New York. "It's impossible to tell where something might be happening. There's no planning for something like that."

Hyden Chaim, a musician and author, went to a band called Frog Eyes at a music event venue called Baby's All Right in Williamsburg on Friday night. And said, "I thought, what's the likelihood of getting bombed at such an obscure band's show? But I'm sure the people in Paris were thinking the same way."

United States' law enforcement agencies had responded by having a sharp alert. Surveillance of Americans who are under investigation because of connection to ISIS are planned to be increased by the Federal Bureau of Investigation.

N.F.L and N.B.A promised to increase security for a crowded timetable of weekend games.

"All of us were just a little more on edge," Khori Petinaud, 28, an actress in the Broadway show "Aladdin" said.  "It's a vulnerable position, being onstage in front of 1,800 people, not knowing if there's one person who wishes someone harm."

"It feels like there are some people who just don't like modern life and reject modernity,"  Joe Lynn, 38, said.