Postgres statement blocks another table's statement

I am running a script that queries table t1. No foreign keys, nothing. Then I executed truncate t2 and realized that it gets blocked by my first statement:

 blocked_pid | blocked_user | blocking_pid | blocking_user | blocked_statement |        blocking_statement
-------------+--------------+--------------+---------------+-------------------+-------------------------------------
        1522 | postgres     |        29470 | postgres      | drop table t2;    | SELECT * from t1 where name = 'test'        

Can anyone help me understand why this happens?