Kattegat was on high alert, the citizens were reckless as the damage control was handled quite poorly. This was bad news as unrest was the last thing they needed but what was more worrying was that Lagertha was nowhere to be seen despite searching every nook and cranny of Kattegat.
They suspected that Lagertha was dead but they could not see her in the heaps of bodies that were found around the city, so the next possibility was that she was taken or hiding somewhere.
It was unlikely that she was hiding when Kattegat was under attack but it was not impossible.
Herfjötur managed to kill more than 30 warriors despite being injured, she was that strong as she fought all night alone and managed to come out alive.
She was in the healer's house and she was being taken care of, the injuries she sustained were not life-threatening, it was like she only defended against the vital strikes because she knew there was no way for her to defend herself against all attacks.
Creation is hard, cheer me up!