A major police operation is now underway to find the man.
“We suspect he attempted to rape her,” said Commander Jens Mårtensson at Stockholm Police.
Police were given a man’s name, but after enquiries on Sunday morning it turned out that he was believed to be staying outside the area.
The guard was on her way to inspect a building when she was attacked. Her hands were tied behind her back, but she managed to struggle free and press her portable attack alarm.
A colleague then came to her aid, and she was then able to reach a security post at the factory, at about 4:10 on Sunday morning. From there she alerted the police.
On Sunday morning nine patrols, two from Uppsala county and two from Stockholm county, were searching for the attacker.
The woman was in shock following the attack and was taken to Stockholm’s Södersjukhus hospital for care. She also had minor cuts. She was due to be questioned by police on Sunday.
Police are due to carry out a forensic examination of the scene.