From the BBC:
Police said "the danger is not over" and warned the public to stay away. The extent of the injuries is unclear - but police say no officers have been shot.
"This is currently seen as an attempted murder, arson and aggravated weapons offence," they said in a statement.
The shooting - which occurred just before 13:00 (12:00 GMT) - apparently targeted a Komvux, or adult education centre.
These centres are attended primarily by people who have not finished primary or secondary school.
Police say students at nearby schools are being kept indoors "for security purposes".
"The news of an attack at Orebro is very serious," Justice Minister Gunnar Strommer told public broadcaster SVT.