¶ NAIROBI, Kenya — A Somali lawmaker was gunned down on a Mogadishu street on Wednesday, a day after four explosions in several neighborhoods of Somalia’s capital killed at least one person and injured several more, including government soldiers.

The Shabab, who are behind much of the violence that plagues the capital, claimed responsibility for the blasts, but not the assassination of the Parliament member, Aden Bule Mohamoud, a former army colonel. It was not immediately clear what other militia or faction might have killed him, or why.

After losing repeated battles both to African Union peacekeepers in Mogadishu, as well as to Kenyan troops in southern Somalia, the Shabab have reverted to guerrilla warfare, both inside Somalia — where they have targeted civilians — and in Kenya, where they have done the same.

In the attacks on Tuesday night, grenades were lobbed at government residences and government peacekeeping positions in three areas of the Somali capital after evening prayers. A grenade lobbed at the residence of a government official near Mogadishu airport injured two of his staff, another struck in the same area, a third exploded near the strategic Bakara market and one caused a blast in a northeastern neighborhood.

“This was Shabab,” said a spokesman for the militant group, Ali Mohamud Rage, in a telephone interview. “They are the enemy. Whenever you get a chance to kill the enemy, you have to do it. We are the ones who are attacking now; they will not attack us anymore.”

The attacks came after the Qaeda-linked Islamist rebel group held a mass rally on Tuesday in Marka, a coastal city 45 miles south of Mogadishu that they control.

According to Kenyan and Somali news media, nearly 1,000 Shabab militants ordered local residents to gather and observe a sort of military parade in which the militants flaunted their armed might on land and sea, brandishing weapons and firing them from motorcycles and from speedboats off the coast. During the spectacle, the militants reiterated threats to attack neighboring Kenya, which has sent its soldiers into Somalia to fight the Shabab, as well as Ethiopian troops that habitually crisscross the Somali border.

Photographs of the event posted on a Somali Web site used by the Shabab show hundreds of Somalis watching a parade of militants with AK-47s, spears and bows and arrows, as well as people playing on the beach.

The Shabab spokesman, Mr. Rage, said the event was a celebration of the Muslim holiday of Id al-Adha. “We are doing this in order to show that we are not against your happiness,” he said. “There was no political issue.”

Days earlier, the African Union peacekeeping mission advertised its own successes with photos of Somalis playing at a beach in Mogadishu.

Kenya’s military has vowed to stay in Somalia until it rids the south of the Shabab, but there are already signs that the incursion may lead to a larger conflict.

The Kenyan town of Garissa was hit with a grenade attack on a church on Saturday night that left two dead. On Friday, armed men opened fire on a vehicle carrying two tourists from Switzerland on a safari, leaving their driver dead. Separately, a police officer was also shot dead during a heavy gun battle with militants only several kilometers from the Somali border.

Kenya’s Foreign Ministry summoned the Eritrean ambassador to Kenya last week to discuss allegations that weapon-laden aircraft from Eritrea were landing in the Shabab-controlled city of Baidoa, and said that Kenya would consider “reviewing diplomatic ties” with Eritrea, according to a prominent Kenyan newspaper.

In a press release last week, the government of Eritrea called Kenya’s comments “extremely regrettable,” and apparently took a jab at Kenya’s military operation in Somalia, saying there was “no military solution” to the decades of insecurity in the Horn of Africa nation.