The [censored] molerats refuse to die when they attack omg, it to me like 15 stimpaks with 4 people 7-10 weapons aproximately

Apparently you don't want to upgrade your rooms till you have powerful weapons and everyone's level 40-50 or so.

Thanks for the tip

Yep, I demolished all my 3lv rooms and built again with max 2lv + at the moment I'm at 28 dwellers and don't want to go any further until I rise SPECIAL stats of my dwellers

Wait for the Deathclaws... You will smash your phone frome anger

I've just started having molerats attacking. I have about 40 people in my vault and only 1 or 2 are above level 20. I haven't been having any issues with them. They pop up, my people kill them, and the event is over. No one has any particularly spectacular weapons either. Most of them have shotguns or rifles.

Same here. I just started getting molerat attacks yesterday with my vault population at 30 or just below. I've got a few dwellers above 20 - as long as the molerats don't spread to other rooms, they go down fairly quickly from dwellers armed mostly with lever action and hunting rifles, a few pistols and couple of rusty laser pistols.

No deathclaws yet - I haven't even built the radio room yet for fear of triggering them.

For me it stays like 1 molerat and 4 people keep shooting him for 2 minutes for him to die

Mole rats are easy, and death claws didn't make it past my first room. Do they get harder with higher levels? All my dwellers are level 17- level 25

Mole rats, rad roaches, and fires scale with the room level they spawn in. Raiders and deathclaws scale with your dweller's average level.