This is a breaking news story. Check back for updates.
UPDATE 4:15 p.m. EST: CCSU Police Chief Chris Cervoni said that no weapons have been recovered, but police are going back to the James Hall dorm to search the room further. Authorities are also looking into whether the suspect was wearing a Halloween costume, which had been reported by some media outlets.
UPDATE 4:09 p.m. EST: New Britain Police Chief James Wardwell says police received more than one 911 call. He said none of those calls reported shots fired.
UPDATE 4:05 p.m. EST: Cervoni said there are "three people of interest right now in custody." He would only confirm that one of the people in custody is a CCSU student. He said a call came in about someone concerned about an individual on the campus wearing camouflage and carrying a "sword-like weapon or handgun."
UPDATE 3:27 p.m. EST: Local television station WFSB in Hartford reports that at least two people are in custody.
UPDATE 3:19 p.m. EST: The lockdown at CCSU has been lifted. "The sounds that you just heard was campus police indicating that the campus is ALL CLEAR #ccsu. You may now leave the buildings," according to a message on the school's Twitter account.
UPDATE 3:01 p.m. EST: A suspect is in custody, CCSU said on its Twitter account. The school said all students should shelter in place "until police make the all clear." A news conference about the incident was scheduled for 4 p.m. EST.
UPDATE 2:52 p.m. EST: Central Connecticut State University canceled classes. But the lockdown remains in place. "We are still in shelter mode," the school said on its Twitter account.
UPDATE 2:48 p.m. EST: CCSU says James Hall residents are being questioned by police.
UPDATE 2:12 p.m. EST: Authorities are talking to a man holed up in a dorm in CCSU's James Hall, the Hartford Courant reported.
UPDATE 1:55 p.m. EST: CCSU said reports of a suspicious person carrying a gun on the Central Connecticut State University campus prompted the lockdown. This is the first explanation from the New Britain, Conn., school since the lockdown was initiated more than an hour ago.
UPDATE 1:53 p.m. EST: The suspect that prompted the CCSU lockdown has been "contained," according to the Recorder, a student newspaper. The lockdown hasn't been lifted, however.
UPDATE 1:14 p.m. EST: Two nearby schools in New Britain -- HALS Academy and Holmes Elementary School -- were on modified lockdown due to the situation at CCSU, according to WFSB.
UPDATE 12:58 p.m. EST: A witness reported a man with a gun near James Hall, according to WFSB. Students said they didn't hear any shots fired on the CCSU campus.
UPDATE 12:53 p.m. EST: The Recorder is reporting that police activity at CCSU is concentrated on James Hall. There's still no word as to what prompted the lockdown.
UPDATE 12:49 p.m. EST: There isn't an active shooting on the CCSU campus, according to the Twitter account for the student newspaper:
â€” The Recorder (@TheRecorder) November 4, 2013
Central Connecticut State University is under lockdown Monday as police responded to the New Britain, Conn., school.
The CCSU Twitter account ordered students to remain indoors and to stay away from windows, but gave few details as to why the lockdown was instituted. It’s unclear whether a gunman was spotted at the school’s New Britain campus or if shots were fired at the college.
#CCSU police is on the scene. Please stay indoors and away from windows.
— CCSU (Central) (@CCSU) November 4, 2013