According to LastPass their team found and blocked suspicious activity on their network. They claim that no evidence that any encrypted user vault data (where the passwords are stored) was taken.
However they said that the investigation has shown that LastPass account email addresses, password reminders, server per user salts, and authentication hashes were compromised.
“We are confident that our encryption measures are sufficient to protect the vast majority of users. LastPass strengthens the authentication hash with a random salt and 100,000 rounds of server-side PBKDF2-SHA256, in addition to the rounds performed client-side. This additional strengthening makes it difficult to attack the stolen hashes with any significant speed.”
It is suggested that you change your master password and if that same password was used on any other sites, you should change it there as well.
For the full communication from LastPass visit here.