Schools brought in counsellors for students who witnessed an incident at Caringbah railway station on Wednesday morning.
Trains were suspended between Sutherland and Cronulla after a woman was injured by a train at the station during the morning peak.
Emergency services including NSW Police, Fire & Rescue NSW and NSW Ambulance were called to the station at about 8am.
A NSW Ambulance spokeswoman said paramedics attended and treated a woman for almost an hour before she was taken to Royal Prince Alfred Hospital.
Dozens of school children were either on the platform or at the station when the incident occurred.
Many were left stranded after trains were stopped between Cronulla and Sutherland in both directions.
Sydney Trains said all trains were suspended due to a person injured by a train, and buses were requested to ferry stranded passengers to their destinations until services resumed a few hours later.
A NSW Education spokeswoman said a number of students from various NSW government public schools witnessed the "distressing incident at Caringbah station on Wednesday, February 17".
"All schools were proactive with support," she said.
"Students from each of the schools were met by staff on arrival and provided with support by school counsellors. Counsellors [were] also available for students [on Thursday] and will be ongoing, as required. The NSW Department of Education arranged for alternative transport for some of the high school students to their schools."
"Parents and carers of students who witnessed the incident were contacted by each of the schools."
Among the schools to arrange transport and support was Cronulla High School, which sent an email to parents at 9am on Wednesday.
"Unfortunately, there has been a serious incident at Caringbah train station this morning, which some of our students have witnessed," it said. "If your child did witness this or is distressed then we have support in place here at school.
"If you are in contact with your child and they need support then please direct them to our head teacher well-being."
The school brought in counsellors and police to speak with students.
Our Lady of Mercy Catholic College at Burraneer emailed parents on Wednesday morning and said the school principal was on route to the station.
In a follow-up email the next day, the school said some students witnessed the "distressing incident".
"We have asked all of our staff to be available and keep an eye on our students ... and all affected students have been provided with counselling support," the school wrote.
"Should your child inform you that they have viewed or heard something about the incident ... they may experience emotional distress and require psychological assistance."
"Grieving and anxious children may not always have the words to talk about what they are experiencing."
If you or someone you know is experiencing difficulties, the following organisations can help.
Lifeline: 13 11 14
Headspace: 1800 650 890
Mental Health Access Line: 1800 011 511
Parent Line: 1300 130 052
Kids Helpline:1800 551 800
Beyond Blue: 1300 224 636
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