From your photos and your description it looks like you may have Fire Blight.

It affects many apple and crabapple trees. There are no know varieties that are totally resistant. 

Fire blight will not usually kill a mature tree unless it is extensive and persistent of several years. Treatments have to be applied early - as in before you see the symptoms.Though unsightly, it’s too late to treat it now anyway. You may want to consider that for next year. 

If the damage is not too extensive, you can prune out the dead branches but be sure to clean your tools in-between cuts so as not to spread the blight.

It looks like this is a large tree which will probably mean hiring a tree care professional if you are considering using a pesticide next year. This year, keep your tree well watered if we enter a hot dry summer. All of our trees are stressed now because we have been experiencing a 3 year drought.

https://extension.umn.edu/plant-diseases/fire-blight

https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional

Pesticides are usually not necessary to control fire blight in Minnesota. They should be used only if fire blight continues to be a yearly problem in your yard.