Some Virginia Tech officials knew about the first shootings at the Blacksburg university in April 2007 and had locked down their offices about 20 minutes before student gunman Seung-Hui Cho burst into Norris Hall, chained its doors shut and killed 30 people before taking his own life, according to e-mails and memos released Tuesday by lawyers of the victims’ families.

The co-director of the university office responsible for emergency response planning sent an e-mail to her family before a campuswide emergency e-mail was sent out, and forwarded the emergency alert to people outside of the university before police arrived at Norris Hall, according to lawyer Peter Grenier.