Police commissioner urged Boston residents to stay in their homes as hunt continues of the remaining suspect of Monday's Marathon bombings.
The emerging debate about whether the Boston bombing holds any lessons about the U.S. immigration system made its way onto the floor of the U.S. Senate Friday, in the first hearing on a reform bill unveiled this week.
Sen. Chuck Grassley, who is from Iowa and is the Senate Judiciary Committee's senior Republican, said in opening statements in the hearing: "Given the events of this week, it's important for us to understand the gaps and loopholes in our immigration system.”
"How can we beef up security checks on people who wish to enter the United States? How do we ensure that people who wish to do us harm are not eligible for benefits under the immigration laws, including this new bill?"
Chuck Schumer, D-N.Y, rejected such a connection and cautioned against conflating the Boston events with a new immigration bill.
Schumer is one of the Senate’s so-called “Gang of Eight,” four Democrats and four Republicans who drafted a sweeping immigration bill that, among other things, strengthens border security and provides a pathway to legalization for undocumented immigrants.
"I'd like to ask that all of us not jump to conclusions regarding the events in Boston or try to conflate those events with this legislation," said Schumer when he spoke after Grassley.
"In general, we're a safer country when law enforcement knows who is here," and has photos and background checks, Schumer added — steps that would be taken in regard to the 11 million people here illegally under the legislation Schumer sponsored with seven other senators.
Though long awaited, the hearing the bill, which would remake the U.S. immigration system, was overshadowed by the drama in Boston, where police were hunting one of two ethnic Chechen brothers alleged to have carried out the bombings and the other was killed.
The brothers’ father, Anzor Tsarnaev, spoke with The Associated Press by telephone from the Russian city of Makhachkala on Friday after police said one of his sons, 26-year-old Tamerlan, had been killed in a shootout near Cambridge, Mass. and the other, Dzhokhar, was being intensely pursued.
The brothers reportedly came as many as a decade ago, some published reports said, perhaps with other relatives as refugees. They are said to be originally from the war-torn Russian region near Chechnya.
Schumer said the U.S. refugee and asylum programs have been "significantly strengthened" in the past five years so that authorities are more careful about screening people coming into the country, but he said if that more changes are needed, he's committed to making them.
Advocates who are calling for more lenient laws regarding the undocumented watched the day’s news with concern that it could affect the rare momentum immigration reform has enjoyed this year.
Those who favor stricter immigration laws, and who have been critical of the Senate bill’s provisions to give undocumented immigrants a chance to legalize their status, seized on the Boston bombing suspects’ foreign roots to question what they see as weak links in the reform measure.
“Our hearts go out to the people of Boston,” said Frank Sharry, executive director of America’s Voice, a group that advocates for immigrants. “They have been attacked, they are under lock down and our thoughts and prayers are with them. The facts on the ground in Boston are very fluid. It’s premature to jump to final conclusions about the attackers.”
“And it’s shameful that some on the far right are politicizing and demagoguing this issue,” Sharry said. “This is no time to single out immigrants or blame any ethnic or religious group. It is a time to come together as a nation and stand with the people of Boston.”
Mark Krikorian, executive director of the Center for Immigration Studies, which favors strict immigration enforcement, said the Tsarnaev brothers’ immigration status may not have “direct” impact on the effort to overhaul the system, but it will likely have some effect.
“What it shows is that immigration security is not divisible, that is, you can’t pick and choose what countries or group you’re going to pay lots of attention to. You can’t say, ‘We going to worry about people from Saudi Arabia, but not Russia.’”
The brothers are believed to have come when they were minors, and could have developed extremist views here, experts say. In that case, immigration checks and balances would not have prevented their alleged actions.
"Herman Cain's 2,000-mile electrified fence would not keep them out," Krikorian said, referring to the former candidate for the GOP presidential nomination. "That's not to say there shouldn't be more fence, but it wouldn't have stopped this."
The immigration legislation would strengthen the border with Mexico, allow tens of thousands of new high- and low-skilled workers into the country and provide an eventual path to citizenship to the 11 million people here illegally. Senators debated Friday whether the bill would provide economic benefits to the U.S. or hurt wages for U.S. workers.
The Associated Press contributed to this report.
Elizabeth Llorente is Senior Reporter for FoxNews.com, and can be reached at Elizabeth.Llorente@Foxnews.com. Follow her on Twitter @Liz_Llorente.