Walker, Obama and Republican presidential nominee Mitt Romney issued statements condemning the attack, in which six people were killed. The alleged gunman also is dead after being shot by an officer.
On Sunday, Obama also received an update on the condition of the injured victims and directed the federal government to assist as necessary in the investigation, which is being led by the FBI.
“As we mourn this loss which took place at a house of worship, we are reminded how much our country has been enriched by Sikhs, who are a part of our broader American family,” the president said in a statement.
Romney called the attack “a senseless act of violence that should never befall any house of worship.”
Walker said his administration was working with the FBI and local law enforcement.