A crisis group assembled to provide support for Kolmården's employees, and the woman's relatives have been notified, reported news agency TT.
The incident occurred just after 11am on Sunday morning. According to eye-witness reports, the woman went into the enclosure, was surrounded and then attacked, wrote the Aftonbladet newspaper.
Emergency services were alerted at 11.11am, and were initially unable to approach the woman.
“You can't just go in to a pack of wolves. Police and ambulance staff couldn't get close to the victim until later,” said Norrköping's emergency services coordinator Jan Tengeborg to the newspaper.
According to Aftonbladet, emergency services are currently attempting to sedate the other wolves nearby.
“It's very unusual for something like this to happen, but it has happened before," Olof Liberg, wolf expert at Sweden's University of Agricultural Sciences (Sveriges lantbruksuniversitet, SLU) said to TT.
“Zoo animals aren't afraid of humans and accidents can happen,” he continued.
Liberg has yet to familiarize himself with this specific case, but said that accidents like this one often occur because of a breach in routine, and notes that wolves are especially dangerous when a zookeeper goes in alone.