Shannon,Sister (15) of Erin Gallagher has taken her own life. RIP

The teenage sister of a schoolgirl who committed suicide less than two months ago has died.

Shannon Gallagher, 15, who paid emotional tributes following 13-year-old Erin's death, was found dead in Co Donegal last night.

It is believed she had also killed herself.

The Donegal VEC, which runs Finn Valley College in Stranorlar, which both girls attended, said they were "trying to find the words and response to the tragedy".

"The school would still be in crisis mode," chief executive Shaun Purcell said.

The Gallagher family, from Ballybofey, were said to be "completely distressed" by the tragedy.

Erin had posted comments on a social networking site before her death on October 27, reacting to people she claimed had been bullying her.

Investigations were launched into claims that she had been a victim of cyber bullying.

A crisis incident team has been put in place at Finn Valley College after staff were notified of Shannon's death this morning.

Two psychologists, guidance counsellors, principal Frank Dooley and other teaching staff are meeting to assess how to support students.

Shannon was found dead at about midnight last night.

A Garda spokeswoman said she was found in a townland known as Stranamuck, near Castlefinn, Co Donegal, several miles from her home.