Manchester Victoria railway station has reopened after three people – including a police officer – were stabbed there on New Year’s Eve.
A man and woman in their 50s and the officer were attacked by a man with a knife at about 20:50 GMT, police said.
The victims’ injuries were “serious” but not life-threatening.
A man has been held on suspicion of attempted murder. The BBC understands the security services are assisting Greater Manchester Police.
Manchester Metrolink said services to the station are operating “to the normal pattern” but advised of “minor delays”.
Officers said counter terrorism police were leading the inquiry, but they were keeping an open mind on the motive.
The officer, a police sergeant in his 30s, was stabbed in the shoulder and released from hospital on Tuesday.
The Home Secretary Sajid Javid said he wished those injured a “full recovery”, as a news conference to update media on the incident was due to take place in Manchester.
BBC 5 live producer Sam Clack, who had been at the station at the time, said he saw a man stabbed on a tram platform at the station, which is next to Manchester Arena, “feet from me”.
Mr Clack also said he heard the knifeman shouting “Allah” during the attack, along with a slogan criticising Western governments.
He added he was “close to jumping on the tracks” as the attacker had a “long kitchen knife”.
Greater Manchester Police, which declared the attack a “critical incident”, said it understood that people would be worried but there was “no intelligence to suggest that there is any wider threat at this time”.
Mr Clack said he first “heard this most blood-curdling scream and looked down the platform”.
“It looked like they were having a fight, but the woman was screaming in this blood-curdling way. I saw police in high-vis come towards him. He came towards me.
“I looked down and saw he had a kitchen knife with a black handle with a good, 12in blade. It was just fear, pure fear.”
He said police used pepper spray and a Taser on the detained man, who he said had been “resisting arrest”.
He said he saw “six or seven” officers on top of the man, who he described as “very skittish”.
“He was very aggressive and very intent on causing more harm than he actually did,” he said.
“It was very, very scary.”
Police said the woman had injuries to her face and abdomen and the man had injuries to his abdomen.
The New Year firework display in Albert Square went ahead.
Assistant Chief Constable Rob Potts said: “A man is in custody and there is currently no intelligence to suggest that there is any wider threat at this time.
“While we don’t yet know the full circumstances and are keeping an open mind, officers from Counter Terrorism Policing North West are leading on the investigation.”