"As we do when confronted by moments of darkness and challenge, we must now come together as one American family. All of us must have the people of Aurora in our thoughts and prayers as they confront the loss of family, friends, and neighbors."
Mitt Romney, Republican presidential candidate:
"Ann and I are deeply saddened by the news of the senseless violence that took the lives of 15 people in Colorado and injured dozens more," he said in a statement. "We are praying for the families and loved ones of the victims during this time of deep shock and immense grief. We expect that the person responsible for this terrible crime will be quickly brought to justice."
Colo. Gov. John Hickenlooper:
"This is not only an act of extreme violence, it is also an act of depravity. It is beyond the power of words to fully express our sorrow this morning. Our prayers and condolences go first to the families of those killed, and we share the grief of everyone affected by this senseless event. We appreciate the swift work by local, state and federal law enforcement. Coloradans have a remarkable ability to support one another in times of crisis. This one of those times."
Janet Napolitano, Secretary of the Department of Homeland Security:
"I am deeply saddened by the terrible shooting in Aurora, Colorado. Federal, state, and local law enforcement agencies continue to respond to this horrific event and I have directed the Department of Homeland Security to provide any support necessary in the ongoing investigation. We are committed to bringing those responsible to justice. Our hearts and prayers go out to anyone impacted by this tragedy, especially the family and friends of those killed or injured."
Andrew Arulanandam, spokesman for National Rifle Association:
"Our thoughts and prayers are with the victims, their families and the Aurora, Colorado community. The NRA will not be making any further statement until all the facts are known."
Dan Gross, president of Brady Campaign:
"As someone who has suffered the lasting impact of gun violence, and president of Brady, I can tell you that we don't want sympathy. We want action. Just this past April 16, the anniversary of the worst mass shooting in American history, 32 victims of gun violence joined us to demand Congress take action to stop arming dangerous people."
House Speaker John Boehner:
"Confronted with incomprehensible evil, Americans pull together and embrace our national family more tightly. I join President Obama, and every American, in sending my thoughts and prayers to the victims of this awful tragedy. We will all stand with them, as one nation, in the days ahead."
New York City Mayor Michael Bloomberg:
"You know, soothing words are nice, but maybe it's time that the two people who want to be president of the United States stand up and tell us what they are going to do about it, because this is obviously a problem across the country. And everybody always says, 'Isn't it tragic,' and you know, we look for was the guy, as you said, maybe trying to recreate Batman. I mean, there are so many murders with guns every day, it's just got to stop. And instead of the two people — President Obama and Gov. Romney — talking in broad things about they want to make the world a better place, okay, tell us how."
House Minority Leader Nancy Pelosi:
"As local law enforcement, first responders, and medical professionals work tirelessly in the aftermath, the federal government will be a partner. As families confront this tragedy, the nation and its leaders are praying for them."
Colo. Sen. Mark Udall:
"I am deeply saddened and outraged by these senseless and tragic shootings. My thoughts go out to the families and friends of those killed, and I am praying for a speedy recovery for those who were wounded. My staff and I are in close contact with officials on the ground and will offer any federal resources needed to investigate this terrible crime and bring those responsible to justice."
Colo. Sen. Michael Bennett:
"This was horrible, senseless and abhorrent act. My family and I are shocked and deeply saddened this morning and our hearts are with the victims and their families. My staff and I are in contact with and offering our support to law enforcement and medical officials as they respond to the shooting."
Colo. Rep. Cory Gardner:
"Colorado and the nation woke up this morning to news of horrendous tragedy; our prayers are with each and every one of the victims and their families. Law enforcement is doing what they do best — acting bravely in the face of violence and we are all grateful for their service. In the hours and days to come, we will learn the answers we so desperately seek to fully understand what happened."
Senate Republican Leader Mitch McConnell:
"This senseless massacre of so many innocent people gathered with friends and family in a movie theater reminds us not only of the great evil that exists in the hearts of some, but of the great and precious gift of life. I join all Americans today in prayer for the victims, their families and friends, and the wider Aurora community, and in heartfelt thanks to all the first responders who quickly responded at great risk to themselves."
Former Virginia Gov. Tim Kaine, who was in office during the 2007 Virginia Tech shootings:
"I am heartbroken and shocked by the horrific act of violence in Colorado. The thoughts of Anne and I are with the families who have lost loved ones in this senseless tragedy. We continue to pray for the recovery of those who have been wounded, and we offer our support to Governor Hickenlooper and the entire community of Aurora as they heal."
• Compiled from staff and wire reports