Merseyrail Northern line services were disrupted after reports of concerns for a woman's welfare.
British Transport Police were called to the line near Bootle New Strand railway station at 1.06pm today (Monday).
An ECHO video shows a number of police cars and a police van near a railway bridge on Knowsley Road.
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A number of police officers are gathered at the bottom of stairs which are used for rail workers to access the bridge.
Eye-witnesses have also reported seeing fire engines and paramedics on Knowsley Road.
Rail replacement buses have been running between Sandhills and Hall Road.
Merseyrail says services on this line may be delayed or cancelled at short notice.
Some trains from Southport were been cancelled this afternoon.
Two fire engines and the search and rescue team arrived at Knowsley Road at 1.48pm, with a Merseyside Fire and Rescue Service spokesperson saying their attendance was to "assist police".
A Merseyside Police spokeswoman told the ECHO: "We were contacted at around 1pm today (Monday) following reports of concern for the safety of a woman at Bootle New Strand Rail Station.
"Police negotiators attended and the incident was resolved at around 4pm. The woman has been taken to hospital for assessment.
"Knowsley Road was closed towards the roundabout but has since been reopened.
"Thank you to local residents for their patience while we dealt with this matter."
Merseyrail says a limited rail service is operating between Liverpool Central and Hunts Cross, and also between Hall Road and Southport.
Disruption is currently expected until 6pm.
Anyone affected may be entitled to a refund or compensation. More information can be found here.
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