The teenager, who on Tuesday was named by police as Lisa Holm from Skövde, was last seen at a café where she worked at around 6:30pm on Sunday evening when she finished her shift.
On Tuesday police found parts of a phone and a mobile case around one kilometre from the café. They are now concentrating their search on a 300-metre radius in that part of the rural region.
“We have expanded the search area and this morning a large number of dog handlers are searching the area,” said Ulla Brem a spokesperson for Västra Götaland police.
A helicopter and two horses are also involved in the search mission.
Police have established a command centre at Källby sports grounds near where the café is located.
On Tuesday police released a photo of the missing teenager in the hope of receiving more clues from the public.
Police say they have received several tip-offs from people who were around the café at the time when the girl was last seen.
“It shows an incredible and positive involvement that people are getting in touch with police,” said Brehm.
But she did not elaborate on what kind of information locals had revealed.
“It’s difficult to say what they have given so far, but we are actively working to investigate the tips,” she added.
Several voluntary organizations have offered to help with the search including the charity Missing People.
“It’s all about the security aspect of the evidence. Missing People understand that it is the police’s job to look first and it is not possible for them and other volunteers to help,” said Brehm.
Police said they were not looking for any specific suspects in connection with the girl's disappearance.