By JIM KUHNHENNWASHINGTON (AP) â¿¿ Three days into a government shutdown, President Barack Obama pointedly blamed House Speaker John Boehner on Thursday for keeping federal agencies closed, while the bitter budget dispute moved closer to a more critical showdown over the nation's line of credit. The president canceled a trip to Asia to remain in the capital as the Treasury warned of calamitous results if Congress fails to raise the debt limit. Answering Obama, Boehner complained that the president was "steamrolling ahead" with the implementation of the nation's new health care law. As the government operated sporadically, the stock market sank to its lowest level in nearly a month. The shutdown was clearly leaving its mark. The National Transportation Safety Board wasn't sending investigators to Tennessee to probe a deadly church bus crash that killed eight people and sent 14 others to the hospital. The Labor Department said it wouldn't release the highly anticipated September jobs report on Friday because the government remains shuttered. Late Thursday, the White House announced that Obama was abandoning an already abbreviated trip to Indonesia and Brunei next week in the face of the shutdown. White House spokesman Jay Carney said Secretary of State John Kerry would travel instead. Earlier, outside the Capitol, shots rang out at midafternoon bringing an already tense Congress under lockdown, a nerve-wracking moment in a city still recovering from a Sept. 16 mass shooting at the Navy Yard. Authorities and witnesses said a woman tried to ram her car through a White House barricade then led police on a chase that ended in gunfire and her death outside the Capitol more than 1 mile away. Despite the heated political rhetoric, some signs of a possible way out of the shutdown emerged. But the state of play remained in flux. Two House Republicans said Boehner told them he would allow a House vote on restarting the entire government â¿¿ but only if conservative GOP lawmakers assured him they would not attack it for failing to contain curbs on the health care law. So far they have been unwilling to give that commitment. The two spoke on condition of anonymity to reveal details of private discussions.