President Obama on Sunday visited the new national park near Shanksville, Pa., which has been established as a vast memorial to the 40 passengers and crew members who died on United Airlines Flight 93 on Sept. 11, 2001.

Obama and his wife, Michelle, laid a large wreath of white flowers at the center of a marble wall bearing the names of those killed and spoke with bereaved relatives. The wall was unveiled Saturday at the park’s opening ceremony.

A crowd of several hundred had gathered to see the president and attend a memorial service earlier in the morning that marked the 10th anniversary of the crash. Park police on horseback patrolled the hills around the central field, while army officers stood on the roofs of the entrance gates. Other park police officers patrolled the paths into the central field.

During the memorial ceremony, family members announced the names of the loved ones they lost on Flight 93. Each name was followed by two somber bell chimes.

A children’s choir from nearby Johnstown sang the national anthem. Wally Miller, the county’s coroner, who recovered remains from the crash site, read a litany.

Many in the crowd wore T-shirts bearing the Stars and Stripes, the logo of the local volunteer fire service that rushed to the crash site or the names of those killed. Ten years on, many of them were reflecting on how Sept. 11 had changed America and shaken their perceptions of their country.

“We’ve realized that we’re not seen as benevolent leaders around the world,” said Norman Simard, a human resources manager from Indianapolis who had extended a business trip to Pennsylvania just to attend the ceremony.

“We need to find a way not to be aggressors even though we still need to protect our interests.”

For many in the crowd, the top concern 10 years after the terrorist attacks seemed to be the flagging economy rather than national security. Some remarked that the rush of patriotism in the years just after the attacks had since faded amid other concerns.

“We need to get America going again,” said Doug Mink, a high school teacher from Cincinnati. “I don’t feel like we’re at the forefront of things anymore.

“For example, this memorial still needs $10 million to be finished. If the economy was better, that would not be a problem.”

The 1,500-acre park has cost $52 million to date and requires $10 million more for features such as a visitors’ center.