英国官员：情报部门知悉曼彻斯特爆炸案嫌疑人的情况

British police say they have arrested three more people in connection with the investigation into Monday's deadly bombing after a concert in Manchester.

A statement Wednesday from Greater Manchester Police said only that the arrests came after officers executed warrants in South Manchester. There was no information about how the three men, or a fourth man arrested Tuesday who was only identified as a 23-year-old, might be involved in the attack.

British interior minister Amber Rudd said Wednesday the suicide bomber, who has been identified as 22-year-old Salman Abedi, was "known" by British intelligence services before the bombing. She also told the BBC that "it seems likely, possible, that he wasn't doing this on his own."

Investigators have been working since Monday's attack to determine if the bomber was part of a wider group.

Mark Rowley, who heads the National Counter Terrorism Policing, described the investigation late Tuesday as "making good progress" and following a number of leads. But he said authorities cannot yet say if the Abedi acted alone.

His comments came after a panel that sets the country's terrorism alert level raised it to critical, or the highest step, signaling that another attack was highly likely and could be imminent.

The change is most visible in the deployment of soldiers to help guard certain areas, including major events such as concerts and football matches, in order to free up police officers.

The blast at the conclusion of a concert by American pop star Ariana Grande at Manchester Arena killed 22 people and wounded 59 others. The attacker also died at the site.

Islamic State is claiming it was behind the attack, but neither British nor U.S. intelligence have confirmed that.

英国警方表示又逮捕了三人。他们跟星期一曼彻斯特一场音乐会后发生爆炸的调查有关。

大曼彻斯特地区警方星期三发表声明只说，警察执行了在南曼彻斯特的逮捕令，逮捕了那些人。现在还没有那三名男子以及星期二被逮捕的第四名男子可能跟袭击事件有什么关联的信息。警方只是说，第四个被逮捕的人23岁。

英国内政大臣拉德星期三说，星期一在曼彻斯特一次音乐会后进行炸弹袭击的自杀炸弹杀手先前已经受到英国情报部门的注意。拉德在接受英国广播公司BBC采访时还说: “看来他这次有可能不是单独行动。”

调查人员自星期一以来一直在试图确定炸弹杀手是不是某个团伙的一部分。

英国全国反恐警察负责人罗利星期二晚上说，调查正在“取得良好的进展”，有若干个线索。但是他说，有关当局还不能确定阿拜迪是否是单独行动的。

在此之前，英国当局一个负责掌管全国恐怖预警级别的委员会将恐怖预警提升到紧急级别，也就是最高级别，显示另一场袭击很有可能发生，或即将发生。

为了让警方腾出更多的警力，英国军人被调派协助守卫一些区域，其中包括重大活动场所，如音乐厅，足球场。

美国流行歌星爱莉安娜·格兰德音乐会结束之际发生的爆炸导致22人死亡，59人受伤。自杀炸弹杀手也当场死亡。

伊斯兰国声称袭击是它策动的，但英国和美国情报部门都没有证实这一点。