LITS (Logical Puzzles Series #4)

There are many puzzles that remained unpublished for many years. Today LITS puzzle is one example of a such puzzle, I created it long back but I have not published it. This is the reason I have started the Logical Puzzles Series to re-publish these puzzles. LITS puzzle is one of my favorite puzzles and it recently appeared in the Indian Sudoku Championship 2015.

Now I am publishing this LITS as the 4th puzzle in the Logical Puzzles Series. Can you solve this LITS puzzle?

Rules of LITS puzzle

Blacken four cells in each outlined area so that each area includes one Tetromino shape. Tetrominoes may be rotated and/or mirrored. Blackened cells should form a single interconnected area that does not have any 2x2 square fully painted black. The same tetrominoes cannot touch each other from the sides, but they may touch each other diagonally.