To commemorate that awful day.  Be kind to one another today.

The New York City Fire Department’s 5-5-5-5 bell calls will sound around Cape Ann on Sunday morning.

Fifteen years after hijacked jets crashed into New York’s World Trade Center, the Pentagon outside Washington, D.C., and into a field in western Pennsylvania, fire departments around Cape Ann will host ceremonies commemorating the terrorist attacks of Sept. 11, 2001. And New York’s 5-5-5-5 signal — the call sounded there as a firefighter’s final bell, said Gloucester Deputy Fire Chief Barry Aptt — will be part of the services.

All the Cape Ann services will be Sunday morning, loosely in line with the time line of the attacks, which killed 2,996 people, left more than 6,000 injured, and led to an undetermined number of later deaths of responders who sustained lung damage from air pollution at the World Trade Center site in New York City.

On that clear Tuesday morning, the hijacked United Airlines Flight 11 out of Boston’s Logan International Airport and bound for Los Angeles crashed into the north tower of the World Trade Center at 8:46 a.m. A second plane, United Flight 175, also out of Boston and bound for Los Angeles, then slammed into the WTC’s south tower at 9:03, while united Flight 77 out of Dulles International Airport in Virginia crashed into the Pentagon outside Washington at 9:37.

United Flight 93 out of Newark International Airport in New Jersey crashed into a field in Somerset County, Pennsylvania, after passengers who had contacted family members and friends mounted an effort to overtake the hijackers.

The schedule of Cape Ann events commemorating the 15th anniversary of the attacks Sunday is as follows:

GLOUCESTER: Gloucester Fire Chief Eric Smith will open ceremonies at Central Fire Station at 9:55 a.m., with announcements over the Fire Department’s radio channel calling for a moment of silence to remember those lost in the 2011 attacks.

The brief ceremony will include the sounding of the bells, with the full department at attention in dress uniforms. The dismissal from the ceremony is targeted for 10 a.m.

ROCKPORT: Rockport’s 9/11 memorial service will begin at 8:30 a.m. at the Central Station on Broadway.

Members of the town Fire Department, in full dress uniform, will then march to T-Wharf for a memorial service slated to begin at 9 a.m.

ESSEX: The Essex Fire Department will host a 9/11 memorial service beginning at 9:55 a.m. in front of  Memorial Fire Station at 24 Martin St.

Fire Chief Daniel Doucette said all retired firefighters and members of the public are are welcome to attend the brief program.

MANCHESTER: The Manchester Fire Department will hold its 9/11 memorial program starting at 9:45 at the fire station, 12 School St.

Chaplain David Forsythe will serve as the primary speaker, and, as with the other Cape Ann services, residents are encouraged to attend.