A gamma squeeze is frequently compounded by the action of a short squeeze. When a stock has a significant amount of Short Interest and price moves rapidly higher above key resistance levels, investors who are short the stock suddenly must also scramble to find shares to buy to cover their position before their position moves further against them.
At this point there are three groups of people scrambling for shares and each are somewhat insensitive to price.
1) MMs who are short calls must buy shares to stay neutral
2) Short sellers must buy to close positions to avoid losses (alternatively, some may buy calls or make other options plays to help offset losses.)
3) Speculators are buying in hopes of cashing in on a parabolic move higher.