The home side Djurgarden felt they should have had a free kick when Ghanian midfielder Yussif Chibsah went down in the centre of the field clutching his face.
But, instead, play continued and Mjallby scored the opening goal of the game moments later through Robin Stromberg.
As Stromberg celebrated with his team mates, irate fans threw beer bottles, fruit and coins on to the field and Mjallby defender Gbenga Arokoyo appeared to be hit in the stomach by a bottle.
After a discussion with match officials, referee Tobias Matsson ushered the two teams off the pitch at Stockholm Stadion and a decision was taken almost 45 minutes later to abandon the match.
"It feels bitter and tough, it's among the most serious things that can happen. I think it's very sad, as do 99.99 percent of those here," Djurgarden chairman Tommy Jacobson told the television channel CMore.
Jacobson said he expected the remainder of the match to be played on another date but Swedish football association match delegate Rune Nilsson said no decision had yet been taken.
"I will write a report, the referee will write a report, and then the disciplinary committee will make a decision," he said.